Something interesting occurred last night when I went over to Xbitlabs (http://www.xbitlabs.com). I went and read the review on Dual 6800s in SLI, and apparently, it received a thumbs up from the reviewer(s). However, not too long ago, I also read this (http://www.xbitlabs.com/articles/video/display/leadtek-sli.html) review on two 6600GTs in SLI. I have been following that review for quite some time and have read it on various websites. Each and every time, the 6600GT SLI setup received a thumbs down from the reviewer.

That is something I simply do not understand. If a vanilla 6800 is only supposed to be slightly faster than a 6600 GT, then why did the 6800 SLI setup receive praise, while the 6600 GT SLI setup has received negative reviews virtually everywhere?

Overall, the 6600 GT performs about the same as the 6800, but for a cheaper price. That's why I recommend it. In those reviews, however, you can see that they trade blows. Sometimes the 6600 GT comes out ahead because of its higher fillrate and faster RAM with lower latencies. Other times the 6800 comes out ahead because of its raw RAM bandwidth and 2 more shader units (5 vs 3).

However, put them both in SLI and things change... Now the 6800's in SLI deliver more power because of the doubled specs. 24 pipelines beats out 16 pipelines. 2 x 256-bit RAM bus widths beats out 2 x 128-bit RAM bus widths, despite the 1GHz RAM speed on the 6600 GT's. And of course 10 shader units is going to pummel 6 shader units, even though the 6800 core speed is much lower. Individually they are very close, but SLI magnifies the power of the 6800.

On a price/performance ratio (between these two vid cards), a single 6600 GT reigns supreme (for single vid card systems), while two 6800's in SLI make more sense (for SLI systems). On the other hand, I still don't recommend the 6800 overall because two 6800's in SLI still cost too much money for what you get. If you really want that extra level of performance, spring for a 6800 GT, which gives you more pipelines and faster clock speeds across the board. Two 6800 GT's in SLI is much more powerful than two 6800's in SLI. Heck, just one 6800 GT gives two 6800's in SLI a good chase!

As for that "thumbs down" review of two 6600 GT's in SLI, that was specifically referring to the SLI kit where two vid cards are sold in one package. That's just plain silly! SLI is meant for either going full-blown, or for upgrading. If you're going to buy a 6600 GT, buy just one. If you have the money for two right away, don't fill both your slots! Buy a 6800 GT instead. That way you get a more efficient use of your money now, and you still have a slot left for SLI later. That was the point of that review. Why buy two mid-range cards up-front when just one high-end card makes more sense?

The real lesson is to read the reviews carefully. Just because the review concludes one thing, it does not mean that it's 100% all of the time. System B might get a poor review or not win the Editors choice, but it might be the system for you, base your decisions on who the reviews apply to you.

It is a bit odd though. I looked at the 6600GT SLI kit that Xbitlabs reviewed. All of the benchmarks seemed to be fine, in that a pair of 6600 GTs in SLI were as fast as a single 6800 GT (give or take 5fps...I mean, who is going to notice the difference between 55fps and 60fps?) However I did notice that SLI failed to function in certain games, and in those situations, only one of the two cards were working.

For example, when comparing the benchmarks in Chronicles of Riddick, the 6600 GT SLI setup, as seen here (http://www.xbitlabs.com/articles/video/display/leadtek-sli_7.html), functions as only a single 6600 GT, as SLI doesn't work. However, when comparing the vanilla 6800s in SLI in the same benchmark (but at a later date), SLI can be seen functioning, right here (http://www.xbitlabs.com/articles/video/display/msi-nx6800-sli_7.html)

As you can see, the same benchmark was used (Chronicles of Riddick). In the 6600GT SLI scenario, SLI failed to work, but in the 6800 scenario, SLI worked beautifully. Why? I looked at the test setup for both of the reviews. the 6600GT SLI kit used version 71.89 drivers, whereas the vanilla 6800 setup used version 77.72 drivers.

Hmmm, interesting: SLI failed to work in a 6600GT SLI setup with version 71.89 drivers, but SLI worked beautifully in a 6800 SLI setup with version 77.72 drivers...in the SAME benchmark!

Can one logically conclude that the 77.72 drivers fixed some issues with SLI? Hence the functioning of the 6800 SLI setup in the Chronicles of Riddick game?

This begs the question...if version 77.72 drivers were used on the 6600 GT SLI setup, would it make SLI function properly? Would it change the outcome of the benchmarks? Would it change the conclusion of the authors?

Edit*: While I have found that most sites that review a 6600 GT SLI setup generally recommend getting a single 6800 GT instead, aren't there certain advantages to dual 6600GTs over a single 6800 GT? Such as noise, heat, and energy required to power the cards?

Can one logically conclude that the 77.72 drivers fixed some issues with SLI?They probably did. Every new driver version is released because it fixed a certain problem or provides better performance. There's quite a big difference (in version number) between 71.89 and 77.72. I would say that SLI was tweaked and/or fixed in many areas.

This begs the question...if version 77.72 drivers were used on the 6600 GT SLI setup, would it make SLI function properly? Would it change the outcome of the benchmarks? Would it change the conclusion of the authors?It would probably make SLI function properly, but I can't read the reviewers' minds! :p It does beg the question, though I doubt the overall conclusion would have been drastically affected by just one of the many benchmarks.

aren't there certain advantages to dual 6600GTs over a single 6800 GT?Two 6600 GT's are cheaper if you buy them one at a time over the course of an upgrade cycle. Otherwise, no, there's no advantage to having two 6600 GT's. While the heat dissipation and power consumption of the 6600 GT is indeed less than the 6800 GT, two of them are not. That's two GPU's and the same amount of RAM sucking power and producing heat, and you've also got more overall PCB and circuitry. Based on the merits of two 6600 GT's vs a single 6800 GT, the 6800 GT comes out ahead. It's more efficient and won't suffer from a possible breaking of SLI performance.

It does beg the question, though I doubt the overall conclusion would have been drastically affected by just one of the many benchmarks.
I see, well, I intended for the one benchmark to simply be an example. I didn't feel like putting in all the other scenarios where SLI did not function properly with the earlier 6600 GT SLI kit review.

But the point is, since most sites seem to note that since SLI is not guaranteed to work in all situations, then going for a 6800 GT would be better than dual 6600 GTs. However, with the newer version drivers, SLI is significantly improved, and therefore, works in many more cases.

Many of the reviews for a 6600 GT SLI configuration gave it a thumbs down mainly because of that reason: that it was not guaranteed to work in all cases...that a 6800 GT would be able to deliver the max performance in all cases. However, all those reviews were done quite some time ago, with older drivers. The newer drivers seem to have fixed that issue, and SLI now works in many more situations; but you don't see any sites reviewing any more 6600 GT SLI setups now, do you? :P

Do you think that if a 6600 GT SLI setup were tested with some newer drivers, then perhaps less sites would give it a thumbs down, and more thumbs up?

Do you think that if a 6600 GT SLI setup were tested with some newer drivers, then perhaps less sites would give it a thumbs down, and more thumbs up?Quite possibly. But the way I see it, you have to keep your own perspective when checking out reviews. You have to look at it from your own usage and budget and what you think is best for you.

For instance, if you only have $120 to spend on a vid card, who cares about two 6600 GT's in SLI vs a single 6800 GT? You can't afford even one 6600 GT, let alone two of them or a 6800 GT! At that point, the merits of either one (and the reviews) are moot. They don't apply. Or if you have $600 to spend on a vid card, again, who cares? You've got enough for a 7800 GTX! Or let's say you have just a single PCIe x16 slot because you didn't get an SLI chipset. Now you've got the doors wide open! You don't even have to consider NVidia only, you can pick an ATI vid card!

When I look at performance reviews, I just look at the numbers. Then I draw my own conclusions. That means I have numbers in my head all day long :rolleyes: but I can't help it if I'm a thinker...