What Graphics Card Do I Need?

[astral]

I have a relatively old desktop with a Intel 850 mainboard with Pentium 4 1.7Mhz.

The graphics slot is rated at AGP x4.

What happens if I put a x8 card in? Will it work?

I have a great deal on a Sapphire ATI Radeon 9550SE 256MB card which is x8.

Or would I do better to look for an old x4 card?

Funds do not permit a complete upgrade at this time, but the kids want to play games.

Edited January 4, 2006 by astral

[The Coder]

Yes, you can run an 8x card in a 4x mobo. In fact I have an Intel 850 mobo, Pentium 4, and run an agp 8x card (radeon 9700). The benefits of 8x over 4x are only a few percent. The card you choose is the key to performance! It's not the agp level, pci-x, how much memory is on it, how new it is, or how high the model number is. Let benchmarks be your guide.

The 9550SE is a crippled dog to be frank--too slow for newer games like doom3. For reference, my card is 4 year old, 128MB and way faster than the 9550SE 256MB and I can handle newer games like doom3. You should strongly consider getting a card with a little more zip. A few hundred baht extra might give you double or triple the performance.

Edited January 4, 2006 by The Coder

[rio666uk]

not wanting to step on The Coders toes - a quick google revealed this - hope it helps.

AGP Speeds are required to be backwards compatible. This means that an 8X video card MUST be able to run at 4x, 2x, or 1x speeds. However, this does NOT necessarily mean that your 8X card will run on a 4x slot.

Signalling Voltage incompatibility

Because speeds must be backwards compatible, Signalling Voltage is where incompatibilities arise. Basically:

* All 8x cards are 0.8v AGP 3.0 spec

* 8x cards will fit in 1.5V slots, and can tolerate the voltage, but will NOT run properly

* 4x cards can be either 1.5V or 0.8V

* 2x and 1x cards are either 3.3V or 1.5V

* Except in the case of the 8X cards, using the wrong voltage card with the wrong motherboard can result in damage in card and board

* If you install a card of incompatible voltages with the motherboard's specs, the card will NOT run

The connectors on AGP video cards are keyed in such a way that you can only install equipment that have compatible Voltage keyed connectors. Normally the key of the card determines its signal voltage. AGP 1.0 and AGP 2.0 cards using a 1.5V key will signal at 1.5 volts. However, AGP 3.0 devices can tolerate 1.5V - they won't be destroyed, they just might not work properly.

The bottomline is that your 8X video card can theoretically be safely TESTED in any 1.5V motherboard for compatibility. But if you know for a fact that your board only runs 1.5V AGP 2.0 spec and your 8X AGP 3.0 card runs only 0.8v spec, then the two should NOT be compatible one another. At the very least it will be unstable, if it runs at all. However, we've had a lot of users tell us that their AGP 8x cards work on 4x only motherboards. This is likely due to the fact that some AGP8X video cards are in fact universal 1.5V capable AGP3.0 cards that can run on either 1.5V or 0.8V (remember, AGP speeds are backwards compatible, only voltage incompatibilies cause problems).