AMD's Radeon HD 5870: Bringing About the Next Generation Of GPUs
by Ryan Smith on September 23, 2009 9:00 AM EST- Posted in
- GPUs
Left 4 Dead
Valve’s venerable Source engine continues to roll on with Left 4 Dead, their co-op zombie shooter. As the Source engine is CPU limited, this is once again going to be a collection of ridiculously high frame rates.
Once again the 5870 is the king of single-GPU cards, putting away the GTX 285 by 36%, and even managing to beat the 4870 X2. The GTX 295 continues to get the best of the 5870 however, leading by a slimmer 8% margin. The difference is once again academic however, as all of these cards are pushing more than 100fps. Interestingly, the 5870 CF doesn’t completely dominate the field as it usually does – it can only beat the GTX 285 SLI by 9%.
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BoFox - Friday, November 6, 2009 - link
Yep, that's turning up LOD to -1 or -2 depending on which game. It was done in Crysis, and with LOD at -2, it looked sharp with SSAA.The Wasrad - Wednesday, September 23, 2009 - link
Why are you using 4 gigs of ram with a 920?Do you understand how DDR3 memory works?
Ryan Smith - Wednesday, September 23, 2009 - link
Error when writing the chart. It has been corrected.Sc4freak - Wednesday, September 23, 2009 - link
Do you? The fact that the i7 920 works best in a triple-channel configuration has nothing to do with the fact that it uses DDR3.chizow - Wednesday, September 23, 2009 - link
Agreed and to add to that, the fact the third channel means very little when it comes to actual gaming performance makes it even less signficant. As compared to Lynnfield clock for clock, which is only dual channel:http://www.anandtech.com/cpuchipsets/showdoc.aspx?...">http://www.anandtech.com/cpuchipsets/showdoc.aspx?...
Von Matrices - Wednesday, September 23, 2009 - link
Could someone enlighten me as to why the 4870 X2 could be faster than the 5870 in some situations? It was noted it the article but never really explained. They have the same number of SP's, and one would expect crossfire scaling to be detrimental to the 4870 X2"s performance. Would this be indicative of the 5870 being starved for memory bandwidth in these situations or something else?Dobs - Wednesday, September 23, 2009 - link
4870x2 has 2Gb of DDR55870 only has 1 until the 2Gb edition comes out :)
nafhan - Wednesday, September 23, 2009 - link
Doesn't using dual GPU's effectively halve the onboard memory, as significant portions of the textures, etc. need to be duplicated? So, the 4870x2 has a memory disadvantage by requiring 2x memory to accomplish the same thing.chizow - Wednesday, September 23, 2009 - link
Right, with an X2 each GPU has a copy of the same frame buffer, so the total memory onboard is effectively halved. A 2GB frame buffer with 2 GPU is two of the same 1GB frame buffer mirrored on each.With the 5870 essentially being 2xRV790 on one chip, in order to accomplish the same frame rates on the same sized 1GB frame buffer, you would expect to need additional bandwidth to facilitate the transfers to and from the frame buffer and GPU.
chizow - Wednesday, September 23, 2009 - link
Ya he mentions bandwidth being a potential issue preventing the 5870 from mirroring the 4870X2's results.It could also be that the 5870's scheduler/dispatch processor aren't as efficient at extracting performance as driver forced AFR. Seems pretty incredible, seeing as physically doubling GPU transistors on a single die has always been traditionally better than multi-GPU scaling.
Similarly, it could be a CPU limitation where CF/SLI benefit more from multi-threaded driver performance, whereas a single GPU would be limited to a single fast thread or core's performance. We saw this a bit as well last year with the GT200s compared to G92s in SLI.