I have an 8800GTS(640MB) and I am curious if I go with SLI do I have to by two of the same exact GPU's or can I use the 8800GTS and then get an 8800GT OC and it will still be just fine? Anyhow thanks for the info ahead of time!
8800GTS and 8800GT won't run together in SLI .... you'd need to buy another 8800gts 640mb to SLI. Though thats a very bad idea....you ought to ideally dump that GTS and get a new single GPU like Radeon 4850 or 4870.
Do the cards have to be same model?
I answer it with an example:
You have a NVIDIA Geforce 7800GTX 256, and you want to add another card , the second card has to be 7800GTX exactly.
But what about the memory? Can you add a 7800GTX 512 and use that with 7800GTX 256?
It's recommended to use a 7800GTX 256 with a 7800GTX 256 and 7800GTX 512 with 7800GTX 512.
However you can use a 7800GTX 256 with 7800GTX 512 , BUT the 7800GTX 512 will lower its clock to operate with the 256 one , so it wont have its true power. (This option isn't recommended )
What about brands ?
Well the brand doesnt matter , again for example , you can use a XFX card with a EVGA card , or a SAPPHIRE card with a DIAMOND card , just make sure they have the same memory and same clocks.
atm stay with nvidia and thiers no reason you cant go sli gts since you already have one card. once again before buying a second card check
make sure its a gts
double check motherboard can do it
check you psu can handle it (for 8800gt/gts 650w qaulity psu minimum)