JohnnyJazz Posted June 12, 2014 Share Posted June 12, 2014 Yesterday I went to buy a HDMI card. I took my desktop with me to be sure the card was working fine. I also wanted to buy one or two big internal HDD. For the time being I use an USB HDD. The vendor told me that the power supply needed to be changed for a more powerful one. I was not really convinced, if I can use an external disk with the current power supply, why should it be any problem with an internal one ? I tried to read the specification on my power supply but that's not really clear. And how can I calculate the power supply I need based on what is installed in the computer ? PS : For people interested in this matter, I found this site : http://extreme.outervision.com/psucalculatorlite.jsp Link to comment Share on other sites More sharing options...
Pib Posted June 12, 2014 Share Posted June 12, 2014 What size power supply do you have now? But anyway, based on your minimal description of your current system, 500W should be more than enough...maybe play it safe with 600W. Use this NewEgg.com Power Supply Wattage Calculator to help determine what size you need. Link And of course there is "quality" differences between power supplies of the same wattage...don't buy a "cheap, no name" brand because a quality power supply is critically important to any electronic item. I can't recommend a brand as I haven't owned a desktop for over a decade which is approx when I switched to laptops. Link to comment Share on other sites More sharing options...
sandyf Posted June 12, 2014 Share Posted June 12, 2014 You cannot compare USB devices with normal devices, they are designed to operate at very low power levels. My cooling pad is USB and is rated at 2.35 watts. My external hard drive is USB is rated at 24 watts and has its own power supply. The vendor is probably right in what he said. When the computer was built the power supply would have been the minimum for that configuration. Link to comment Share on other sites More sharing options...
Pib Posted June 12, 2014 Share Posted June 12, 2014 You cannot compare USB devices with normal devices, they are designed to operate at very low power levels. My cooling pad is USB and is rated at 2.35 watts. My external hard drive is USB is rated at 24 watts and has its own power supply. The vendor is probably right in what he said. When the computer was built the power supply would have been the minimum for that configuration. You have your external hard drive in a 24W "self-powered" enclosure, but that does not mean the drive requires/uses anything close to 24W. For example, say a person was to buy this Western Digital internal 3.5" 1TB hard drive shown at this invade website. When using the Go to Manufacturer's Specification page for the drive its 12 Volt power read/write power requirement is 2.28 watts using the formula Power=Current X Voltage and its 5 Volt power read/write requirement is 1.4 Watts....therefore total watts used in read/write mode is 3.68 watts...and this total power requirement is reflected in their power dissipation spec of 3.7 watts. See the cut and paste below from the specs page. Therefore, lets just say a typical internal 3.5" drive uses uses around 4 watts when reading/writing...much less when idle. A 2.5" drive will use even less. And of course a person could also stick this drive in a self-powered external enclosure and the drive would draw the same 4 watts of power from the external enclosure although the self-powered enclosure is generating 24 watts of power....but none of this 24 watts or the drive's 4 watts requirement is being drawn from the computer's power supply....the only thing flowing back and forth between the computer and enclosure is the data stream. Link to comment Share on other sites More sharing options...
h90 Posted June 12, 2014 Share Posted June 12, 2014 If you are not sure, use the old power supply and if you can play a modern game without problems it is strong enough. If you get crashes, you need a stronger one. If it is too much hassle, just buy a stronger power supply. Link to comment Share on other sites More sharing options...
JohnnyJazz Posted June 12, 2014 Author Share Posted June 12, 2014 If you are not sure, use the old power supply and if you can play a modern game without problems it is strong enough. If you get crashes, you need a stronger one. If it is too much hassle, just buy a stronger power supply. 2 Link to comment Share on other sites More sharing options...
CharlesHH Posted June 15, 2014 Share Posted June 15, 2014 If your eyes did not cross reading Pib's message, then you already know your answer. Otherwise, just buy the 750 +- watt supply and relax. The difference in money is small compared to the peace of mind with your data. Note, your UPS backup should be the larger one, too, and there the cost is really a factor to upgrade. 1 Link to comment Share on other sites More sharing options...
AnotherOneAmerican Posted June 15, 2014 Share Posted June 15, 2014 It seems unlikely you would need a bigger power supply. 1 Link to comment Share on other sites More sharing options...
sirchai Posted June 15, 2014 Share Posted June 15, 2014 It seems unlikely you would need a bigger power supply. The guy needs to sell some stuff, C'mon.... 1 Link to comment Share on other sites More sharing options...
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