Ok, here is my dilemma. Is it better to go with say 2 Geforce 7600GS 512MB GDDR2 PCI Express x16 Video Cards in SLI or instead go with 2 Geforce 7600GT 256MB GDDR3 PCI Express x16 cards? Or just go with one of the 7900 models. Basically what is more important # of pixel pipelines, memory clock speed, or sheer memory size? The 7600 GS will give me the most memory at cost of speed and pixel pipelines but it will be in SLI. I can increase speed (at cost of memory) by putting the 7600 GT's in SLI. Or finally I could just get a 7900 model. I won't have enough money to get another for SLI mode though What do you think? Is there another combination I should look at?
Generally speaking, more memory on a slower card won't help you as much as a faster card with less memory. Many times, manufactures like to sell slower graphics cards by slapping more memory on them. 256MB is pretty optimal for many of the mid-level graphics cards. When 512mb is more necessary, it will be more available.
Give what you cannot keep to gain what you cannot lose.