The Odorous One
Banned
- Jul 6, 2008
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Originally posted by: chizow
Since this thread has evolved into a single vs. multi-GPU discussion I'll go ahead and post up a short compilation of the pros/cons I made in a different thread. I have not used SLI/CF in its current AFR form, the last time I had multi-GPU was with 3Dfx and their SFR version of SLI. My list is based on common issues I read about on forums, here and especially game-specific and vendor forums.
Honestly I challenge anyone who has no experience with CF/SLI to try it yourself and prove these issues don't exist before recommending others to go multi-GPU. You can google any of the bullet captions and find tons of evidence on each of the issues listed below. I think the last guy who called BS is off trying to get a single GPU to run, much less a 2nd. I've personally never made a huge issue about CF/SLI because I've never seriously considered going that route even though I had an SLI capable board.
- Profiles/Scaling- SLI/CF rely on driver profiles for their performance and in the case of ATI, you can't change these yourself. So if your particular game doesn't have a pre-defined profile you may see no benefit or even *worst* performance than with a single card. In the case of relying on two individually slower cards than your single card, you can see that you may actually be paying more for *worst* performance which is unacceptable to me. Scaling is typically erratic as well even when CF/SLI is working, so seeing 2x the performance is rare (although RV770 does show improvements here).
- Micro-stuttering- Pretty heated debate about the significance of this problem on this board and others although it pops up infrequently. Basically the timing of each frame from the different GPU in AFR can be erratic, leading to this effect. Apparently some people are very sensitive to it and some aren't. I certainly wouldn't be happy if I spent $400-600 for SLI/CF only to find I couldn't stand micro-stutter.
- Heat/Power/Space - Typically not an issue for most enthusiasts, but it can become a problem when you have 2 or even 3x the power draw and heat from high-end cards. The PSU issue can be a total W issue, but also a power connector issue with so many high-end parts needing 6 or even 8-pin PCI-E connections. Many cases and motherboards can also have problems accomodating 1x9"+ card, much less 2, 3 or 4.
- Multi-Monitor (NV only) - NV multi-GPU solutions do not support multi-monitors. I don't know if this is a superficial driver limitation to prevent desktop cards being used in professional workstations or a truly technical issue, but I'm leaning towards driver limitation as I'm assuming the Quadro GX2 would support more than 1 monitor..... Multi-Monitor support is important to me as I play full screen on my 1920 and use my 2nd monitor for various monitoring tools, surfing the web, and desktop productivity etc.
- Bandwidth/Frame Buffer - Not as big a deal at 1920, but one of the major reasons to upgrade to the fastes GPU is for ultra high resolutions with AA. With a GX2 or SLI/CF solution, you're still limited to the same bus width and frame buffer as the individual cards even if you have more rendering horse power. This limitation is apparent in the higher resolutions with AA when comparing a GTX 280 with a true 512-bit bus and 1GB frame buffer to the X2/SLI solutions with a 256-bit bus and 512MB buffer. R700 addresses this problem somewhat with a larger frame buffer and GDDR5.
- Chipset specific limitations - ATI CF requires an Intel/AMD chipset and NV SLI requires an NV chipset. This unnecessarily ties your platform to your GPU between generations and in the case of SLI, to NV's flaky chipsets.
- Overclocking ability? - NV used to have problems overclocking in SLI in Vista but I think its been fixed. Not sure if ATI has similar problems although I know many of their parts are clock-locked via BIOS. SLI/CF on a single card can also have heat issues that prevent further overclocking.
- Low Minimum Framerates (CP5670 mentioned) - SLI/CF for whateve reasons tend to have much lower minimum framerates than single-GPU solutions. You may not see the difference in AVG FPS as the CF/SLI solution may make-up the difference by rendering less intensive frame sequences at a higher rate.
- Vsync and Triple Buffering consistency problems (CP5670) - seems this can be hit or miss with SLI (not sure about CF) and is certainly an important feature at both high and low FPS. At low FPS Triple Buffering, helps mitigate the incremental FPS denominations of Vsync and at high FPS they can prevent screen tearing on LCDs.
- AFR Input Lag (BFG10K mentioned) - seems inherent to AFR due to the latency between pre-rendered frames generated by the CPU and when they are rendered by the GPU and displayed on-screen.
Again, there's really only 1 person on these forums shouting from the rooftops about how great SLI/CF is. Most everyone else is basing their opinions on how awesome a few numbers and graphs look from a few games without ever having tried it themselves. Then there's the silent few that have tried it, moved on and are quiet about their experience. If you look around and actually read the replies from people who have actually used multi-GPU I think you'll find that the vast majority of responses are quite different. In any single thread over on the EVGA forums about step-up from SLI/GX2 to a single GT200....its quite obvious how much happier people are with their single-GPU set-ups.
Wow, that speech smacks of nVidia, sorry to say. Could it be the GTX 280 you proudly display in your sig?
I'll bet if you bought a couple of 4850's and ran them in CF, you'd be spitting black feathers out your mouth. And you wouldn't feel so bad about spending more money than you had to for less performance.
It's quite comical to read comments such as yours when you never used the product.