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SLI Performance issue

Last response: in Graphics & Displays
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January 26, 2008 4:10:27 PM

I'm trying to run two BFG 8800 GTX oc's in SLI mode and I'm not getting the performance I should be. I've tried to eliminate every bottle neck I can, but it doesn't seem to be improving performance, even though my 3D Mark score is over 10,000. In COD4 my average frames at max settings at 1280x1024 are only around 50, and sometimes dip as low as 25 in some areas. Crysis barely runs at times, and I've seen no performance increase over a single card in Oblivion whatsoever. I feel that I'm clearly doing something wrong here, but I don't know what. I'm still teaching myself the ins and outs of hardware. I went through BIOS and didn't see any SLI settings, but I may have missed something. My system specs are as follows:

2x 8800 GTX OCs (BFG)
Asus M2N SLI Deluxe Nvidia 570 motherboard
AMD 5000+ Black Ediiton, OC'd to 3 GHz
2 GB Corsair Dominator DDR2 1066 (running at 800 since the motherboard doesn't support above that, but this was an addition I made today. I had been running 2 GB of Kingston DDR2 667 utnil this morning, adn there was no performance difference)
SB X-Fi Extreme Gamer
Thermaltake 850W Toughpower Power Supply
Windows XP Pro

More about : sli performance issue

a b U Graphics card
January 26, 2008 4:46:05 PM

What drivers are you using?
January 26, 2008 5:47:28 PM

I had been running the last one until today. Right after I posted I realized I hadn't check that in a while so I got forceware 169.21. After installing that, it now stays steady at 60 fps in COD4, and won't go up (and doesn't usually drop below by much). As I said, the default cap in the game is 80, and I reset it to 100 just to see if that's why it was stuck at 75, but now it's at 60 and won't go any higher. I've tried forcing the different rendering styles (split frame, alternate 1 and 2), and split frame and alternate 2 seem to keep it consistant at 60. Alternate 1 drops below often enough that I can see it drop into the 50s and sometimes below. All of this with the new patch.
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January 27, 2008 11:37:43 PM

Bump. I could really use some help if anyone might have an idea for a fix.
January 28, 2008 12:02:58 AM

I'm sure you are only running one card, my system running one GT gets 10400 in 3DMark 06. Look through the BIOS again there should be a setting to enable SLI or something concerning Nvidia GPU's, also did you enable SLI in the Nvidia Control Panel?
January 28, 2008 12:04:38 AM

Trunnion8 said:
I'm trying to run two BFG 8800 GTX oc's in SLI mode and I'm not getting the performance I should be. I've tried to eliminate every bottle neck I can, but it doesn't seem to be improving performance, even though my 3D Mark score is over 10,000. In COD4 my average frames at max settings at 1280x1024 are only around 50, and sometimes dip as low as 25 in some areas. Crysis barely runs at times, and I've seen no performance increase over a single card in Oblivion whatsoever. I feel that I'm clearly doing something wrong here, but I don't know what. I'm still teaching myself the ins and outs of hardware. I went through BIOS and didn't see any SLI settings, but I may have missed something. My system specs are as follows:

2x 8800 GTX OCs (BFG)
Asus M2N SLI Deluxe Nvidia 570 motherboard
AMD 5000+ Black Ediiton, OC'd to 3 GHz
2 GB Corsair Dominator DDR2 1066 (running at 800 since the motherboard doesn't support above that, but this was an addition I made today. I had been running 2 GB of Kingston DDR2 667 utnil this morning, adn there was no performance difference)
SB X-Fi Extreme Gamer
Thermaltake 850W Toughpower Power Supply
Windows XP Pro


You don't mention the monitor...
January 28, 2008 12:20:42 AM

Well for one, your running 8800GTX's in SLI for 1280x1024. Thats probably your biggest problem. SLI, doesnt scale very well on lower resolutions. Also your processor isnt the greatest.
January 28, 2008 12:34:20 AM

I understand that my proccessor isn't exactly high powered. But at the same time, I should be getting higher frames than this. I see absolutely no difference between a singled card and dual. Even with one or these cards, I should be getting more than 60 fps at this res, but I still top out with one of the cards removed. I went back through the BIOS and couldn't find any SLI settings. The monitor is a Viewsonic VP930b. I'm hesitant to buy a bigger monitor if my frames are only going to suffer if I increase the resolution.
a b U Graphics card
January 28, 2008 1:00:31 AM

For one, grab the beta 169.28 drivers instead of the 169.21 drivers.

Second, you will not see a difference between one and two 8800GTX at 12x10 resolution unless you totally crank fsaa/af. Try running the crysis GPU benchmark with 4xaa enabled within the game and 16xaf forced in the drivers and you should see the SLI start to pull way ahead. Besides Crysis with high fsaa, I really can't imagine SLI giving you a boost over a single GTX at 12x10.
January 28, 2008 1:43:49 AM

I'm downloading the drivers now, but my point right now isn't so much the boost from single to SLI, but the fact that even a single is getting me only 60 fps or less in most new games. Am I wrong in thinking that even a single card should be getting me more than that at 1280x1024 with settings maxed? One of my friends has a single 8800 GTS (G92) and is getting 90 frames with max settings at a higher res. His hardware is comparable to mine in all other respects.
January 28, 2008 2:03:00 AM

I loaded up the new driver and it made no difference. I disabled one card in COD and the frames dropped significantly (45 fps and below). Enabling SLI brings the frames back to a constant 60 (never above)
January 28, 2008 2:20:41 AM

The 169.28 beta driver is said to improve CRYSIS SLI, and not neccesarily other games. I'm running 2 8800 GT's 512 in SLI at 1920x1200 on my ViewSonic 28" playing Crysis at med-high settings only gives me bout 33fps. I havn't installed my COD4 yet, but its graphics aren't quite as advanced as Crysis's, so 45fps single card sounds right. 60fps for SLI is nice, but if wut u say is true and ur friend is getting over 60fps with single card, then u have an issue to sort out lol.

btw, I myself am having problem with SLI. when disabled (single card) I am getting the 33fps with the settings mentioned above, whilst in SLI, i get 10fps. I have downloaded every singel driver for Vista, Nvidia, Crysis, BIOS I could find, but absolutely no improvement. for further details, check out my SLI problem thread: http://www.tomshardware.com/forum/248214-33-crysis-wors...

Oh and btw, I dont have any SLI options in my BIOS either...could be a pattern...
January 28, 2008 2:21:11 AM

I think your CPU bottlenecked. Crysis need a big processor too, and 3DMark06 pays a lotta attention to the CPU.

When you run 3DMark06 where does your system with one card fall in with others just like it? And when you add the second card? And vs something like an Q6600 or E6750 at good OC's?
January 28, 2008 2:40:41 AM

i'm running Q6600, even if it was bottlenecked, i should at least be getting the same results in SLI as in single card config...
a b U Graphics card
January 28, 2008 2:45:46 AM

Well, with the "problem" of it not going above 60fps, either in the game or in the Nvidia Control Panel, Vsync is enabled, so it is matching the refresh rate of your monitor, 60Hz.

Stupid question, but is the SLi bridge connected snugly? I know I've made tons of mistakes like that.
January 28, 2008 3:49:18 AM

Boy,

Hurts me to tell this to you, but I've gone through nearly the same issue as you last week.

I had a X2 4600+, Asus A8N-SLI, 2Gb DDR400, 7800GTX (256mb), Creative X-FI Gamer, PSU Hyper X Tyre R 580W and a brand new copy of Crysis.

First attempt to run the game (I was expecting low-med settings on 1360x768 around 30fps stable) was a disaster. Even with low settings the game was around 15-25 with several slowdowns.

Then I decided "it's time to upgrade this videocard". Farewell 7800GTX, you had been great for the past two years...

Bought a BFG 8800GT OC 512mb and loaded the game (after all driver updates and etc) looking for stable 30+ fps at the same resolution with medium-high settings (I play in a 42" TV and this is the highest resolution that I can get). And the result was: disgusting... Crysis recommended medium settings this time (versus the low in the previous card), but I was still hitting 15 fps many times @ medium settings.

I couldn't undestand what was going on, since I had a dual-core CPU (I agree, an old one), 2gb ram, RAID-0 drives, dedicated sound card... So I started to google everything that you can imagine and also put some posts in forums (like this one) to get some help.

After thousands of reboots, installs, bios flashing, tweaks, oveclocks (I usually do not like to do overclock - neither know how to do it - but I tried) plus everything that you can imagine I still could not improve my results. 3DMark06 was near 9000, with SM2 around 3500 and SM3 around 4200.

Then I saw some links with people with almost the same configuration as mine with similar results. That was the time that I told myself: Face it, this is the best that your system will give to you, so if you want to improve this, better look for new MB, Processor and RAM.

Well, after declaring bankrupcy, bought a C2D E8400, Asus 750i SLI MB and 4Gb of OCZ RAM, praying for good results.

Finally, after the upgrade, I can play Crysis at 25fps stable on Very High Settings (recommended by the game itself) or 30+ on high settings. 3DMark was finally where it should be, over 6000 for video benches. Now I am happy and poor, really poor...

I would never believe if it were with someone else. The same video card with a new processor improved way over 50%. Bottom line, I was told that 8800 needs fast CPUs to shine but I could not believe, now I do. I had to learn it in a very expensive way...

So, If you allow me to give you an advice, I would tell you to upgrade your MB+Processor. This E8400 really rocks. My last four processors were AMDs (Athlon 2200 and 2600, Athlon 64 3200 and the X2 4600) and I was very satisfied with them, until I met again Intel. I have not had any experience with the new Phenom, but now I don't even want to get close to it.

Sorry if I could not help more (and for my english - I'm still learning it...), but to get what you deserve with your nice cards, go for a better processor.




January 28, 2008 6:10:40 AM

thats true, it is a fact that with nowadays games, the PCU counts for almost (if not more) as much as a GPU, and if either one of them can't support the other, your bund to run into a bottleneck
sadly, thats the truth and it hurts all of our wallets :( 
a b U Graphics card
January 28, 2008 11:24:35 AM

Trunnion8 said:
Enabling SLI brings the frames back to a constant 60 (never above)

As was mentioned, this sounds like vsnc is on within game or in NV Control panel (drivers).
January 28, 2008 11:47:40 AM

And the prize goes to jedimasterben! It was the V-sync. It was forcing "on" in nVidia. Disabling it and the application V-sync in COD4 upped the frames dramatically. Now my max hits the limit I set (250) and the lowest it fell was 115. Thank you all very much for your help, it was all greatly appreciated. I definitely learned a few things here.
January 28, 2008 4:54:41 PM

Trunnion8 said:
And the prize goes to jedimasterben! It was the V-sync. It was forcing "on" in nVidia. Disabling it and the application V-sync in COD4 upped the frames dramatically. Now my max hits the limit I set (250) and the lowest it fell was 115. Thank you all very much for your help, it was all greatly appreciated. I definitely learned a few things here.


Wonderful news!
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