IM Buying a mobo with SLI, but only installing 1 card. I have a few questions about upgrading, read details.?

Question

1. What is the point of having 2 cards @ 8x VS. 1 @16x? Would that not cause a bottleneck in speed? Or is it still faster because these video cards are not operating at full bandwidth anyway? 2. Do I have to have Identical video cards in order to SLI them? Like if I have a Geforce 7600 GT now, and my budget allows
me to get a 7950 XTX later, can I hook those suckers together or do I need to 7600 GTs? 3. If I can hook different models of video card together, do I have to stay within a certain generation, like the GeForce 7000 series or can I go balls to the wall and buy an 8000 series card that runs on Direct X 10 and eats other video cards for breakfast? Im sure you cant, but I can't find and documentation about it anywhere and it never hurts to ask.

Please help!

Answer 1

Okay let me take this one at a time. As for having 2 at 8x vs 1 at 16x, it varies depending on the game and the settings. If you plan to invest the money into SLI, you really should invest into something with the 680i chipset, which does allow you to have 2 cards both running at 16x, otherwise there is no real point in spending the big money to run two cards at 8x.

As for what you can SLI together, this is the area that seems to cause the most confusion. First off, different brands is no problem at all. As for different models, yes you can mix different models, but they have to have the same GPU. Most people don't know the name of the GPU used, it is not marketed as part of the card. Here is a link:http://en.wikipedia.org/wiki/Comparison_of_NVIDIA_Graphics_Processing_Units#GeForce_7_series
look under the "code name" column. You can mix any G70 with another G70, but not a G70 with a G73, etc. Keep in mind though, that if you do have two cards with different speeds, the faster card will always slow down to the speed of the slower card, and if they have different amounts of RAM, the extra RAM on one card will be disabled.

I think I already covered part 3 above, obviously 7000 series and 8000 series would have different GPUs, so no you coudn't mix them.

Answer 2

So far we have not hit the full bandwidth available through PCI express 16x, even with the higher end cards. So running two cards at 8x does not create a bottleneck.


Cards in SLI need to be of the same series, preferably the same model in order to ensure memory and core clock rates are as close to each other as possible.

In other words, if you have a 7600gt from XFX and you buy another 7600GT from say, EVGA, you could run into a few problems, though it is rare.


I would suggest right now that you splurge a little on the video card and go for one of the 8600's. They were just released, can be found for about $170 bucks and will destroy the 7600Gt for only about 60 bucks extra.