My median PC bought from ALDI in the UK has a problem

[n210mp]

MY Desktop PC kept turning off every time I turned it on.

Googled the problem and followed the advice of cleaning it all out because maybe it was overheating as the google thinghy said.

I removed the fans, cleaned out all the parts that looked as though they had heat sinks or cooling ribs including the power supply cooling fan.

Boy was it dirty inside and after cleaning it worked perfectly all day

The next day I turned it on and it promptly turned itself off again again and again and again.

I have removed the Power supply but cannot see anything amiss with it like scorch or overheating stains

I am now at a loss.

Has anyone any experience of this type of failure and information where I can get a new power supply unit or have it tested or repaired without high cost.

Edited July 9, 2014 by n210mp

[3NUMBAS]

too many things it can be take to a repair shop

[wolf5370]

I would suggest th CPU is overheating - it will power off as a safety precaution. Is it an Intel? The heat sink from Intel, the little twisty feet, are a real pain to get in properly and locked down. Get yourself some thermal cement (from and computer or electronics company for about 10 baht a tiny tube - which is plenty). Take of the CPU heat sink (clean it if needed - can scrape of the old cement with your finger nail - both on the copper plate on the heat sink AND the top of the CPU (don't worry it is in a metal case) - then replace the cement, with a blob that flattens to about the size of a 1 baht coin - and replace the fane/sink. Make sure none of the feet are loose - Pull up the top of the pin leg, push down the bit below, listen/feel for the slight click, then push the top down and twist locked - do it diagonally.

Edited July 9, 2014 by wolf5370

[Crossy]

Moving to Technology, but it could be any one of a zillion things.

[wolf5370]

Ahhh <deleted>! Crossy you caused my edit to get lost (twice) with that move!

Op: In addition to what I said above, check all cards (memory / PCI / Graphics Card) are seated correctly - take them out and put them back in - include the cabled in that - especially CPU and fan cables.

[n210mp]

Ahhh <deleted>! Crossy you caused my edit to get lost (twice) with that move!

Op: In addition to what I said above, check all cards (memory / PCI / Graphics Card) are seated correctly - take them out and put them back in - include the cabled in that - especially CPU and fan cables.

Thanks for the information Wolfy I will try to follow your advice.

The reason I actually asked for advice is not just because I dont have the funds to keep making the Techies happy down at TukCom when ever I have a problem and especially one that maybe like the above can possibly be sorted by myself.

The fact is that after cleaning everything I could clean it worked albeit only for a full day but then had me thinking that maybe I had cause inadvertently some loss of contact somewhere in the motherboard.

Thanks again and to the other posters for their comments

[n210mp]

Wolfy I did more or less what you said to do, the exception being that the "CPU" was under a mass of aluminium heat sink clusters and also the big fan on top of that took some removing, I had removed the fan previously which was very dirty but hadn't removed the mass Heat sink on top of the CPU

Following the spirit of your advice I removed the heatsink this time and lo and behold the CPU was very dirty, dirty enough to make me think that it has over heated and cooked.

I also cleaned more thoroughly all the other bits and pieces and with few wire plugs left over, put everything back together again.

I checked , double checked and checked again referring to photos that I had previously taken of the complete MB with all the wires plugged in .

Well to my delight it turned on but went into the repair mode, which was great at least it wasn't just turning itself off again unfortunately I hadn't plugged the KB or mouse into the system so couldnt tell it to carry on with a repair, so I turned it off, plugged everything into the PC and tried again.

This time it just turned itself off, time and time again so I think that I may have as I said cooked the CPU.

I think that I have done as much as I can unless you can offer any further advice.

Once again Thanks for your help

[Chicog]

What might have been a Bt200 cleanup job could now be a much more expensive repair.

Best leave these things to the experts I say.

[RichCor]

Does it boot consistently without the Mouse and Keyboard plugged in.

Also, try testing by unplugging ONE powered peripherals and see if it powers-up consistently without that device.

Mouse

Keyboard

DVD/CD ROM

Hard Drive

While it could be ANY issue, it could be simple, like some device shorting the power, or the power supply no longer delivering adequate wattage.

My guess, either the Mouse or Keyboard is short-circuiting or the Power Supply is failing. If it's not one of those...

the only way to test would be by replacing each part until you identified the part or cause (up to and including replacing the operator)

[wolf5370]

Modern CPUs are not easy to cook (like they used to be) - for a long time now they have auto cut outs to stop that.

OK some questions now: - What OS? Does it get to (assuming Windows) the Starting Windows stage or dos it just go straight off without booting at all?

I'll pre-empt (and assume Windows):

Boot and press F8 until you get to the Windows options menu - select "last known good config." and see if that allows for boot up.

Also if you have two memory DIMMS (or more) try swapping their positions (and trying with just one DIMM seated - rotate - memory can cause the problems you are having too)- seems weird but it works sometimes.

Failing that, next thing to test would be you HDD - they are pretty heat sensitive, boot to DOS (in Vista upwards this is not true DOS, but a windows shell - but that's fine as most drivers will have not been loaded)...

- put in a repair disk (if you haven't got one already - they can be downloaded for free from various web sites - download the one that matches your OS). Boot to BIOS and make sure it is set to boot the dvd drive before the HDD in the boot order - pretty easy to find in the menus of any bios system, so don't panic.

Reboot and let the computer boot to repair mode off the disk. Select to go to the DOS prompt and try the following commands - they will take a considerable amount of time (depending on disk size and how many files are on it). [ if OS is not on C, then change to that drive letter - note that sometimes Disk Repair will reassign the C drive to D or E temporarily - so do a dir c:\ etc to check its the right one).

CHKDSK C: /R

Let that finish and it will tell you of any bad sectors etc - and attempt to fix them on the fly.

Next try to repair Windows:

SFC /scannow (this will take forever!)

Check the system memory: Various free memory tester apps out there - you want one with a reboot disk that runs outside of windows (usually uses some kind of Ubuntu build) - MemTest is one such tool (nice and simple) - more on that here: http://www.cnet.com/how-to/how-to-test-your-ram-in-windows/

The next steps after all this - if still no joy - is to go a step at a time. Disconnect HDD and remove any DVD etc - turn on PC and leave it for an hour to see if it powers itself off (it will sit at a prompt waiting for a boot location - just ignore this). It that works, then it is one of two things (well 3, but 2 much more likely in this case): the HDD is failing or the PSU is.

Easiest way to test this is using a swap out for either and see if it fixes. You can also take the PSU out to be tested at a shop - but you can get a new one for 500 baht or so from PC parts shops (gives you a spare at worse). HDD can be cloned at some shops when buying a new one - this will save a lot of heartache trying to copy them over yourself - hope you have important stuff backed up (cock ups have been known - a friend of mine did this and the twit copied the wrong way using some home made cloning software and emptied the disk!).

If it still powers off with the HDD disconnected (from power and data - 2 cables) then try without the monitor plugged it - this is especially true if it is a graphics card and not on-motherboard (as they often draw a lot of watts) - if this fixes (I,e, power light stays on for that hour) then suggest its the PSU again.

If it still fails - then strip the PC down to basics - remove all cards including gfx and memory and unplug all drives (floppy/DVD/HDD/memory card) any external USB connectors too if poss. Then put back just one DIMM (memory) and try the hour test - if it works, go through a step at a time replacing a card/plus/dim etc until it starts to happen. If you find it happens on one thing - then exclude that thing and keep building - then try that thong again and see if it fails again (do this because then you know the thing is the cause and not just that your reached some other threshold and was a coincidence). If it fails stripped down - then try a new PSU in the hopes it is not the MB or CPU.

PC shops will do all the above - although better shops will do it faster as they have DIM testers and PSU testers and spares to swap out each part - but same process is needed.

Have fun

[rhythmworx]

Boot it up and enter the BIOS just leave it there and see if it crashes.

Also in BIOS if you have an option that sounds similar to ..auto restart on error/power failure...disable it. (Hoping this will show a Blue Screen instead of restart so we can note the code and diagnose the problem)

When you say it restarts as you boot it, after how long, do you get to where it lists your drives...the loading windows screen?

Does your computer beep once when you turn it on? It's important the speaker on the chassis is connected correctly as this can also help diagnose problems with its beep codes.

[taotoo]

If you removed the heat sink from the CPU, I imagine you will need to reapply the thermal paste - as it stands it may now be running even hotter than before.

[rhythmworx]

If you removed the heat sink from the CPU, I imagine you will need to reapply the thermal paste - as it stands it may now be running even hotter than before.

True.

If you haven't got any thermal paste, Mayonaisse will be OK as a temporary solution should the local shop be closed..

Seriously I'm not joking.

http://www.hardwaresecrets.com/article/Does-Mayonnaise-Last-as-a-Thermal-Compound/1793

Edited July 9, 2014 by rhythmworx

[n210mp]

If you removed the heat sink from the CPU, I imagine you will need to reapply the thermal paste - as it stands it may now be running even hotter than before.

Thanks for that I did in fact remove vestiges of the paste thinking it was compacted dust, but will renew tomorrow

[n210mp]

If you removed the heat sink from the CPU, I imagine you will need to reapply the thermal paste - as it stands it may now be running even hotter than before.

True.

If you haven't got any thermal paste, Mayonaisse will be OK as a temporary solution should the local shop be closed..

Seriously I'm not joking.

http://www.hardwaresecrets.com/article/Does-Mayonnaise-Last-as-a-Thermal-Compound/1793

Yes thanks for that info maybe in the short term I will try that

[rhythmworx]

If you removed the heat sink from the CPU, I imagine you will need to reapply the thermal paste - as it stands it may now be running even hotter than before.

Thanks for that I did in fact remove vestiges of the paste thinking it was compacted dust, but will renew tomorrow

I recommend you get ceramic paste as it is non conductive.

Don't put too much on, the idea of it is to fill in any micro gaps in the CPU lid and heatsink.

Edited July 9, 2014 by rhythmworx

[n210mp]

Boot it up and enter the BIOS just leave it there and see if it crashes.

Also in BIOS if you have an option that sounds similar to ..auto restart on error/power failure...disable it. (Hoping this will show a Blue Screen instead of restart so we can note the code and diagnose the problem)

When you say it restarts as you boot it, after how long, do you get to where it lists your drives...the loading windows screen?

Does your computer beep once when you turn it on? It's important the speaker on the chassis is connected correctly as this can also help diagnose problems with its beep codes.

Will try this when I have re applied the mayo tomorrow

The last time I tried to start up since I took the heat barrier paste away it came on once and wanted to do a Window repair, I think it then went into a high heat level without the paste and turned itself off

[n210mp]

Modern CPUs are not easy to cook (like they used to be) - for a long time now they have auto cut outs to stop that.

OK some questions now: - What OS? Does it get to (assuming Windows) the Starting Windows stage or dos it just go straight off without booting at all?

I'll pre-empt (and assume Windows):

Boot and press F8 until you get to the Windows options menu - select "last known good config." and see if that allows for boot up.

Also if you have two memory DIMMS (or more) try swapping their positions (and trying with just one DIMM seated - rotate - memory can cause the problems you are having too)- seems weird but it works sometimes.

Failing that, next thing to test would be you HDD - they are pretty heat sensitive, boot to DOS (in Vista upwards this is not true DOS, but a windows shell - but that's fine as most drivers will have not been loaded)...

- put in a repair disk (if you haven't got one already - they can be downloaded for free from various web sites - download the one that matches your OS). Boot to BIOS and make sure it is set to boot the dvd drive before the HDD in the boot order - pretty easy to find in the menus of any bios system, so don't panic.

Reboot and let the computer boot to repair mode off the disk. Select to go to the DOS prompt and try the following commands - they will take a considerable amount of time (depending on disk size and how many files are on it). [ if OS is not on C, then change to that drive letter - note that sometimes Disk Repair will reassign the C drive to D or E temporarily - so do a dir c:\ etc to check its the right one).

CHKDSK C: /R

Let that finish and it will tell you of any bad sectors etc - and attempt to fix them on the fly.

Next try to repair Windows:

SFC /scannow (this will take forever!)

Check the system memory: Various free memory tester apps out there - you want one with a reboot disk that runs outside of windows (usually uses some kind of Ubuntu build) - MemTest is one such tool (nice and simple) - more on that here: http://www.cnet.com/how-to/how-to-test-your-ram-in-windows/

The next steps after all this - if still no joy - is to go a step at a time. Disconnect HDD and remove any DVD etc - turn on PC and leave it for an hour to see if it powers itself off (it will sit at a prompt waiting for a boot location - just ignore this). It that works, then it is one of two things (well 3, but 2 much more likely in this case): the HDD is failing or the PSU is.

Easiest way to test this is using a swap out for either and see if it fixes. You can also take the PSU out to be tested at a shop - but you can get a new one for 500 baht or so from PC parts shops (gives you a spare at worse). HDD can be cloned at some shops when buying a new one - this will save a lot of heartache trying to copy them over yourself - hope you have important stuff backed up (cock ups have been known - a friend of mine did this and the twit copied the wrong way using some home made cloning software and emptied the disk!).

If it still powers off with the HDD disconnected (from power and data - 2 cables) then try without the monitor plugged it - this is especially true if it is a graphics card and not on-motherboard (as they often draw a lot of watts) - if this fixes (I,e, power light stays on for that hour) then suggest its the PSU again.

If it still fails - then strip the PC down to basics - remove all cards including gfx and memory and unplug all drives (floppy/DVD/HDD/memory card) any external USB connectors too if poss. Then put back just one DIMM (memory) and try the hour test - if it works, go through a step at a time replacing a card/plus/dim etc until it starts to happen. If you find it happens on one thing - then exclude that thing and keep building - then try that thong again and see if it fails again (do this because then you know the thing is the cause and not just that your reached some other threshold and was a coincidence). If it fails stripped down - then try a new PSU in the hopes it is not the MB or CPU.

PC shops will do all the above - although better shops will do it faster as they have DIM testers and PSU testers and spares to swap out each part - but same process is needed.

Have fun

Yes thanks again Wolfy I will do all that you suggest in this post, I have copied and pasted onto an A4 sheet and will go through the list after I have re applied the mayo to the CPU top

And yes I am enjoying myself even though its frustrating

[n210mp]

Does it boot consistently without the Mouse and Keyboard plugged in.

Also, try testing by unplugging ONE powered peripherals and see if it powers-up consistently without that device.

Mouse

Keyboard

DVD/CD ROM

Hard Drive

While it could be ANY issue, it could be simple, like some device shorting the power, or the power supply no longer delivering adequate wattage.

My guess, either the Mouse or Keyboard is short-circuiting or the Power Supply is failing. If it's not one of those...

the only way to test would be by replacing each part until you identified the part or cause (up to and including replacing the operator)

Ha Ha Ha I think her who is to be obeyed would agree with your last suggestion about the operator

No it was just turning off straight away but as I said in rely to Wolfy's post I will do as you and He suggested when I have got it all back together again

And thanks for your post

[n210mp]

What might have been a Bt200 cleanup job could now be a much more expensive repair.

Best leave these things to the experts I say.

Thanks for your input and the confidence booster

I dont know in this neck of the woods where you can get a "Techie" to even talk about a problem for 200Baht unless he can see a nice invoice possibly in the region of 3/4K Baht coming his way

They are somewhat like the Doctors around here or should I say "Consultants" who prescribe for profit and not cure who IMHO are coloured in the same color, shady!

I have had this ALDI Median PC now for many years and it is only a standby so I will have a go at sorting it out myself.

Its amazing what you can learn from the "Net" and also the many great posters on here who recognise that the old fart is possibly out of his depth but are still willing to humour me by giving great advice and ergo encouragement

[lostinisaan]

Googled the problem and followed the advice of cleaning it all out because maybe it was overheating as the google thinghy said."

​ Enough to receive the Pulitzer Prize

"

Edited July 9, 2014 by lostinisaan

[paulchiangmai]

I had very similar problems to you , drove me crazy turning off all the time, I cleaned everything but still had the problem, sometimes after a dozen or so attempts it would stay on, finally took it to a shop, the guy immediately found the problem, the video card had a heavy fan attached to it which was causing one corner to sag and disconnecting the connections that plug in, he got one of those plastic ties and supported the sagging corner, charged me 200 baht for the five minutes work, my thoughts were 'get outer here, no way will that fix it', three months later it hasn't stopped yet.

[PiPiFFS]

As has been mentioned. The pc should make a series of beeps before shutting down. These beeps can tell you what the problem is by their number and speed etc. good luck.

[n210mp]

Well I had a day off yesterday with the view that I would start today with renewed vigor.

I have just gone into the work shed and taken the fan and the heat sink off the CPU and was ready to place some mayo when I thought that maybe Mayo whilst a short term problem solver would possibly mean going through this routine again if I was unlucky so I have decided to go into town and try and get some of the ceramic paste.

Getting to this stage though has opened up a new little problem and that is:

How much of the paste or the mayo should I place onto the CPU proper or should I just place the paste in the copper centre in the middle of the heat sink that actually comes into contact with the CPU or do I coat both.

also do I wait for the Mayo or paste to go hardish or off before I marry them up together?

Thanks for the patience I really do enjoy my potterings in the back of my PC

Before I attempt to do this I will await your very welcome comments

[n210mp]

Just re read your post 3 Wolfy and will do exactly as you instruct

[wolf5370]

As has been mentioned. The pc should make a series of beeps before shutting down. These beeps can tell you what the problem is by their number and speed etc. good luck.

Just to add: Some PCs do not beep any more (no internal speaker) - these usually have a strip of LEDs that show the same thing, but will need to look up the motherboard manual for details as to what the code means.

To the Op: Just had another thought: About 5 years ago I had a similar problem on one of my desktop machines. I went through the whole process of checks, including rail testing the PSU and could not figure it out. In he end it turned out to be a dodge power switch, no visible problem at all (no smell or arcing I could see etc) - replaced the switch and all was well. Only was to test for this is to bypass the switch, which means using jumper cables (those ones with the little clips at each end) and being VERY careful doing a live power test. Last resort though - more likely you will find it with what we have suggested above.

[n210mp]

As has been mentioned. The pc should make a series of beeps before shutting down. These beeps can tell you what the problem is by their number and speed etc. good luck.

Just to add: Some PCs do not beep any more (no internal speaker) - these usually have a strip of LEDs that show the same thing, but will need to look up the motherboard manual for details as to what the code means.

To the Op: Just had another thought: About 5 years ago I had a similar problem on one of my desktop machines. I went through the whole process of checks, including rail testing the PSU and could not figure it out. In he end it turned out to be a dodge power switch, no visible problem at all (no smell or arcing I could see etc) - replaced the switch and all was well. Only was to test for this is to bypass the switch, which means using jumper cables (those ones with the little clips at each end) and being VERY careful doing a live power test. Last resort though - more likely you will find it with what we have suggested above.

Yes thanks for that Wolfy

Funny you should mention the power switch because I have this afternoon felt a slight tingle on the main frame whilst working on the PC which wasn't there before.

Since you mention this I also thought I saw a small arc in the vicinity of the power switch but put this down to the phenomenon that you see when you switch a light switch in the dark and see a similar arc, in other words just normal

This afternoon I went to a friendly Computer repair shop down the road and the chap gave me a little of the thermal paste to apply to the Heatsink and CPU

There was a lingo problem but He didn't want to charge me for the paste and I thought if this doesn't sort the problem out I will take the PC to him as a job .

Well I couldn't tell him that I thought I needed more paste He said that the amount He placed on the heat sink core would be enough but thinking of what you advised I didn't think it would be enough to cover the face of the core and the CPU back plate as well ( where they face up to each other that is)

Anyway I went home placed the bits back together again making sure that the CPU was firm in its socket.

I also checked the Sound and Graphic mount and then turned on the power with the HDMI cable plugged in

All the fans were running. the CPU, the PSU and the graphics card

It ran for five seconds Bleeped once on its internal speaker and promptly shut down

I tried to start it 5 time with no bleeps and no response other than it starts and stops.

I then tried without the graphics card, HDMI plugged in and same response

I think that I am now at the end of my potential to do a home repair and because of the fact that the PC is shutting down without a bleep makes me think that the problem is the PSU ( I dont have anything to back this hunch up)

Tomorrow I will take it down the the nice young man who gave me the thermal paste for free and ask him to have a look at it, just him giving that paste gave me confidence that He would be a good guy to trust with my gear.

In any event I have had a great time trying to fathom out the problems with my PC and would like to say a big thanks for the help and info you and others have given

In this thread

[Sayonarax]

PSU is overheating.

Its most likely dusty and hairy.

[wolf5370]

As has been mentioned. The pc should make a series of beeps before shutting down. These beeps can tell you what the problem is by their number and speed etc. good luck.

Just to add: Some PCs do not beep any more (no internal speaker) - these usually have a strip of LEDs that show the same thing, but will need to look up the motherboard manual for details as to what the code means.

To the Op: Just had another thought: About 5 years ago I had a similar problem on one of my desktop machines. I went through the whole process of checks, including rail testing the PSU and could not figure it out. In he end it turned out to be a dodge power switch, no visible problem at all (no smell or arcing I could see etc) - replaced the switch and all was well. Only was to test for this is to bypass the switch, which means using jumper cables (those ones with the little clips at each end) and being VERY careful doing a live power test. Last resort though - more likely you will find it with what we have suggested above.

Yes thanks for that Wolfy

Funny you should mention the power switch because I have this afternoon felt a slight tingle on the main frame whilst working on the PC which wasn't there before.

Since you mention this I also thought I saw a small arc in the vicinity of the power switch but put this down to the phenomenon that you see when you switch a light switch in the dark and see a similar arc, in other words just normal

This afternoon I went to a friendly Computer repair shop down the road and the chap gave me a little of the thermal paste to apply to the Heatsink and CPU

There was a lingo problem but He didn't want to charge me for the paste and I thought if this doesn't sort the problem out I will take the PC to him as a job .

Well I couldn't tell him that I thought I needed more paste He said that the amount He placed on the heat sink core would be enough but thinking of what you advised I didn't think it would be enough to cover the face of the core and the CPU back plate as well ( where they face up to each other that is)

Anyway I went home placed the bits back together again making sure that the CPU was firm in its socket.

I also checked the Sound and Graphic mount and then turned on the power with the HDMI cable plugged in

All the fans were running. the CPU, the PSU and the graphics card

It ran for five seconds Bleeped once on its internal speaker and promptly shut down

I tried to start it 5 time with no bleeps and no response other than it starts and stops.

I then tried without the graphics card, HDMI plugged in and same response

I think that I am now at the end of my potential to do a home repair and because of the fact that the PC is shutting down without a bleep makes me think that the problem is the PSU ( I dont have anything to back this hunch up)

Tomorrow I will take it down the the nice young man who gave me the thermal paste for free and ask him to have a look at it, just him giving that paste gave me confidence that He would be a good guy to trust with my gear.

In any event I have had a great time trying to fathom out the problems with my PC and would like to say a big thanks for the help and info you and others have given

In this thread

The thermal paste/cement isn't contact glue, it just needs to remove the air gap between heat sink and CPU. The heat sink usually has a copper inner on the underside (to aid heat conductivity) and as long as that will be covered when clamped down, then it is fine - too much actually will clog the fins and work against the heat transfer (also will leak down the sides and may even get under the CPU - which is not good. If he was a PC guy, he would know how much to give you. I usually get little 5mg syringes, and that's enough for 2 - really don't need much.

If you feel a slight shock though the frame when its plugged in, this could be that you MB is earthing through the case - sometimes (stupidly IMO) they use metal spacers between the MB (motherboard) and case, these can move slightly if not tight and cause the board to short - this is very bad news as it can cause the MB to burn out (or the tiny capacitors to be reversed and blow) - which would kill the MB. Most are plastic, so can't short - so check that (might mean removing the MB temporarily). More likely though is the switch, PSU or rails (the wire bundles that exit the PSU) are shorting through the frame. A multi-meter can be used to check any small voltage across the box (when off and then when on) - and by pulling the rails out one by one (power off/on between!) might let you know if and where that is shorting. However, this is unlikely to cause the use with restarting you have - unless the PSU is shorting internally and has a safety cut out.

If you saw a spark on the power button, it is not mains voltage at that point, so you should never see a spark! Sounds like a new power button would be beneficial and may be the issue - very chap and easy to replace. The wires from the front can be followed to a small jumper plug inside )will be two plugs for power and can be one, two or three pronged on each - may have a + and - sign on the back or SW etc. Make note of their positions and which may around they go (often they are part of a multi-plug and thus can be plugged in anyway around, but best to be safe), pull them out, the power switch will likely be held in by a screw or two on the underside of the front panel facia, take the lot to you guy and get him to solder on a new switch - don't just get the switch repaired, not worth it - replace it. I do this myself with a soldering iron and a part (switch) from the local electrical outlet (one of those small stores that are always in the BigC/Tesco buildings) - switch needs to be rated at 12V DC.

I think, personally, it is either the switch or the PSU (sniff the PSU WHEN UNPLUGGED!) does it smell of ozone/like its been arcing? You could replace both for less than 1000 baht all told, but take the old OSU with you so they can match th CPU plugs (there are 3 main sizes/shapes of MB plugs).

[Duindam]

Median computers sold by Aldi are budget computers, nothing wrong with that, the only problem is that budget power-supplies are often the source of problems.

If your computer was as dirty/dusty as you say, it's likely that your powersupply doesn't work correctly anymore. Maybe you get 3.1Volt instead of 3.3Volt, or you get 11Volt instead of 12Volt. This is often enough for the strangest problems with computers (including automatic shutdowns).

The good news is that a budget powersupply is not that expensive, you can buy standard 450Watt powersupplies from 350 to 500 THB. The amount of Watt depends on your computer configuration, but I guess you not have an expensive graphics card in your computer and the processor is probably also not the Intel or AMD top model.... so a 450 to 500 Watt budget powersupply will do the job...