I was thinking of going sli and while looking at the prices saw that the 8800 320mb gts is cheaper than the 8800 640mb gts. Can I hook these two up in SLI? Will that work or do they have to be exactly the same?
In theory 'yes' you can, but you will end up with two 320s.
---------------
Forums are like a herd of performing elephants with diarrhoea -- massive, difficult to redirect, awe-inspiring, entertaining, and a source of mind-boggling amounts of excrement when you least expect it.
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 )
---------------
"I ordered to bury my body without coffin untill the ingredients of my body gradually become part of Iran."
The Great Koroosh