im sorry for being stupid but what is sli? i found on the nvidia site that it is something to do with dual graphics cards and sli motherboards. does that mean that you cant use a single sli card? do you need an sli motherboard to use an sli card or does that only apply if you you are using 2 cards? cheers

Yep, you can still use a single card that has SLI.

SLI will have a small connector at the top of the card, which will allow you to attach it to another.

Like I mentioned in your other thread, SLI is used to share the processing power between the two. More specifically, the first card will render to top half of the screen, whilst the other renders the second.

thanks very much. so is it better to go for dual sli 8500gt or a single 8600gt or x1950?

SLI defo, but you need to make sure that your motherboard has two of these PCI-E slots onboard?

i dont quite understand, the 8600gt is sli but if im only getting 1 what does it matter? do i take it that the 8600gt sli is better than 2 8500gt slis?
my motherboard is nvidia geforce 6150. how do i tell if it has 2 pci e slots? im pretty sure it does.

No, two 8500 gt's would be better than a single 8600gt. 8600 GT is a good card, but wouldn't compare to two 8500's.

Right, since you've asked the question, "how do i tell if it has 2 pci e slots?" suggests that we need to take a step back, as you need to be sure before you buy. Before you do, you will need to open up your PC and find out for sure what you currently have.

- First of all, how do you know you even have a PCI-Express Slot?
There are two types of 6150, PCI-Express and AGP. You'll find PCI-Express on most modern motherboards these days, but your motherboard will either have an AGP slot, or a PCI-Express slot. The 8600 GT only comes as PCI-Express (as far as I'm aware).

- Do you have enough slots for SLI?
If you have PCI-Express, your second slot will look identical to each other. It's not standard for a motherboard to have more than one PCI-E (x16) slot unless it is designed for SLI.