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[H] GeForce GTX 700 series SLI review: GeForce GTX 760/770/780 in SLI and 3-way SLI - Page 7

post #61 of 64
Quote:
Originally Posted by malmental View Post

MercurySteam, who's general consensus is that and where did that come from.?
and in gaming the 3770K is just as solid as the 39xx..

Not arguing that the 3770K isn't on the same level as the Extreme chips for gaming. But id like to know why there is such a significant difference between 2-way GTX 780 SLI in the reviews. If you're forking out that much dosh for dual GPUs, then an additional 90% in demanding games should be a given.
post #62 of 64
Quote:
Originally Posted by MercurySteam View Post

Quote:
Originally Posted by malmental View Post

MercurySteam, who's general consensus is that and where did that come from.?
and in gaming the 3770K is just as solid as the 39xx..

Not arguing that the 3770K isn't on the same level as the Extreme chips for gaming. But id like to know why there is such a significant difference between 2-way GTX 780 SLI in the reviews. If you're forking out that much dosh for dual GPUs, then an additional 90% in demanding games should be a given.
http://www.anandtech.com/show/6934/choosing-a-gaming-cpu-single-multigpu-at-1440p
Hurdles with NVIDIA and 3-Way SLI on Ivy Bridge

Users who have been keeping up to date with motherboard options on Z77 will understand that there are several ways to put three PCIe slots onto a motherboard. The majority of sub-$250 motherboards will use three PCIe slots in a PCIe 3.0 x8/x8 + PCIe 2.0 x4 arrangement (meaning x8/x8 from the CPU and x4 from the chipset), allowing either two-way SLI or three-way Crossfire. Some motherboards will use a different Ivy Bridge lane allocation option such that we have a PCIe 3.0 x8/x4/x4 layout, giving three-way Crossfire but only two-way SLI. In fact in this arrangement, fitting the final x4 with a sound/raid card disables two-way SLI entirely.

This is due to a not widely publicized requirement of SLI – it needs at least an x8 lane allocation in order to work (either PCIe 2.0 or 3.0). Anything less than this on any GPU and you will be denied in the software. So putting in that third card will cause the second lane to drop to x4, disabling two-way SLI. There are motherboards that have a switch to change to x8/x8 + x4 in this scenario, but we are still capped at two-way SLI.

The only way to go onto 3-way or 4-way SLI is via a PLX 8747 enabled motherboard, which greatly enhances the cost of a motherboard build. This should be kept in mind when dealing with the final results.
post #63 of 64
Quote:
Originally Posted by Arni90 View Post

This should be common knowledge, but it clearly isn't.
SLI may be better than CFX when it comes to 99th percentile frametime-performance, but it's still not comparable to a single card.

How is it not comparable? I don't follow your reasoning. Please explain.
post #64 of 64
Quote:
Originally Posted by South80 View Post

Finally, a reveiw site that includes frametimes!

Its quite intersting to see that although two gtx 760's are faster then a single gtx 780 the frametime for the two gtx 760's are higher then the single gtx 780.

This is clearly not the case for all, or even most of the benchmarks, as far as I could tell (I didn't tally every single one however). The frametime (incl. 99th percentile) is negatively correlated with fps (although this relationship is not linear). In cases where frametime is substantially higher for the 760 SLI vs. 780 (but framerate is still higher), e.g., Tomb Raider at 3x 1080p w/ 4x AA, are probably the result of reduced memory and/or bandwidth on the 760 cards compared to the 780's (82 vs. 25 ms) . However we're compared 23 fps vs. 20 fps, so how relevant is that to the performance of either setup? It's academic only. Other examples of this difference are when frametimes are better for the 780 at playable frametimes and framerates for both cards, and the difference in frametimes is negligible. So, where is this difference relevant to smooth gameplay that both 760 2x SLI and a single 780 can handle? Perhaps Max Payne at their highest tested resolution (45 vs 28 ms)? I don't know. But it seems to me that if this is a memory size or bandwidth related difference, it is only relevant in a few cases, if any, based on the games tested here.
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