Sign in with
Sign up | Sign in
Your question

Pinpointing sli issues

Last response: in Graphics & Displays
Share
February 16, 2010 3:38:23 PM

Lets get my specs out of the way :
User: been working with computers for about 25 years though this is his first dual gpu rig.
cpu: AMD Phenom 9600 2.3 ghz quad core overclocked to 2.65 ghz (possible red light)
mb: MSI K9N2 platinum 750a sli ami bios (flashed yesterday)
ram: 4 gigs
os: Windows xp 32 (red light there)
gpu's: dual gtx 275's
screen: 21.5 19x10

Issues: You've probably been seeing this all over the net becaus I know I have, but I also have slight performance increases and fewer screen stalls with one of my gpu's disabled via the nvidia control panel. All games and benchmarks. Both cards have been removed and re connected. I have rolled back drivers as far as the 190 from I think July 09'? Currently using the latest beta drivers, they have shown the greatest performance. Bios has been flashed. While I'd like to blame microsoft for everything xp cannot possibly be so bad at handling sli so that one works better than both.

Ami bios has 2 sli settings, under advanced chipset it has hybrid sli. Under cell menu it has sli ready memory. The bios settings for pcie are 16 up and 16 down yet when i run gpu-z it sees they are capable and yet running at 8x. This could also be an issue.

Note: Not pulling one of the gpu's out because it runs faster with the extra throughput from the pcie slot and the bridge. Actually running with both cards installed and one turned off is much faster than just running with just one card installed. I know there are dozens of postings on the net similar to this one but the threads always end without a result or conclusion.

Thanks in advance for anyone who can help me on this issue. Please no trolling here, even if you don't like someones response, just ignore it. Pretty sure I can filter out the results on my own.

More about : pinpointing sli issues

a c 272 U Graphics card
February 16, 2010 3:52:19 PM

A Phenom 1 that's at less than three gig and a pair of GTX275's that would be too much for it even if it was perhaps, I've found that the faster the CPU the better when it comes to SLi.
m
0
l
February 16, 2010 4:02:31 PM

I do realize they are tripping over themselves with shackles on their feet. I have to be honest and say i do find it very hard to believe that bumping my processor up to a 3ghz or faster would make my sli scale that much more significantly.
m
0
l
Related resources
a c 272 U Graphics card
February 16, 2010 4:18:46 PM

I don't think you would get that CPU to 3ghz without it becoming a fire hazard but if you could then you would see gains, whether they would be enough is another matter.
m
0
l
February 16, 2010 6:18:21 PM

I did at one point bring my processor up to 2.8 ghz knowing full well within 20 mins or so my machine would lock up, but just to see if it scaled even a little. It didn't, the single card enabled was still faster. I highly doubt 200mhz would make much of a difference.
m
0
l
a c 272 U Graphics card
February 16, 2010 6:24:52 PM

Maybe that Phenom just can't cut it? I Have not had a chance to play with a pair of 275's so I don't know if an E8400 would be enough even but after having built and played with a few SLi rigs I can tell you now that CPU speed is important and in the case of Intel CPU's the more cache the better.
m
0
l
February 16, 2010 7:10:47 PM

Well just got off the line with nvidia support. They like my system for sli performance, except the power supply. I have to call them back in a bit but they're saying some 650's are just not up to the task.
m
0
l
a c 272 U Graphics card
February 16, 2010 7:22:13 PM

You hadn't mentioned your PSU until now so I assumed that it was a meaty one, what is it then? Although whenever I've run into a weak PSU on an SLi rig it usually manifests as either SLi not being able to be enabled or the option not being given in the NV control panel or a beeping card.
m
0
l
February 16, 2010 8:57:30 PM

nvm I had a bad idea.
m
0
l
a c 173 U Graphics card
February 16, 2010 9:37:35 PM

Check your ram timings since that might be effecting your performance. I had a similar issue but figured out a few ways around it. Also make sure nothing in your rig is over heating including the ram and the NB. As for the overclock it is possible that you may have maxed out your VRM on your board knowing the power consumption of those older Phenom 1 quads. If using a crappy stock cooler ditch it and get a decent copper based cooler. As for the cards they should be doing far better than that. SLI scales really well when configured properly even for low end cards much less your cards.
m
0
l
February 17, 2010 12:03:16 AM

Yeah I actually just started overclocking in response to other threads where people state you need 3 ghz or higher to get it to scale. The north is running at about 62c at load at the moment as well as the cpu, and with each over clock I've done over the last couple days I have seen performance boosts, but the one card enabled still beats it. The sli ready memory function is enabled on my bios, though there really aren't a whole lot of sli settings on ami bios'.

I am going to get to the bottum of this somehow, and I will be sure to post my findings here. I've read many other similar threads and each are left so open ended. It is really starting to look like a psu issue though. I can see the fluctuation in fps, running fraps in the background, with sli. It is really kind of like one card is hungry for some juice when its it's time to render, the fluctuation is in near perfect intervals. Like say stareing at a wall ingame or at something fixed. While running single there is no such fluctuation, or at least none so large. I'm talking a 2-5 fps fluctuation every 2 seconds or so just idling in 3d graphics.
m
0
l
February 17, 2010 12:10:24 AM

Also, thanks a ton for your guys ideas. Very appreciated. Any more tips are very very welcome.
m
0
l
a c 173 U Graphics card
February 17, 2010 1:23:41 AM

OK lets start the process of elimination. First test each card for defects. The psu should have been ruled out by now. Is this 8x8 sli or a 16x8 or 16x16 sli (pci-e ). Is one of the card down clocked in any way from its defaults? What is the timings of your ram? I assume that the cards are not at fault but you never know so start any of the steps as listed at your leisure.
m
0
l
February 17, 2010 2:58:52 AM

nforce4max said:
OK lets start the process of elimination. First test each card for defects. The psu should have been ruled out by now. Is this 8x8 sli or a 16x8 or 16x16 sli (pci-e ). Is one of the card down clocked in any way from its defaults? What is the timings of your ram? I assume that the cards are not at fault but you never know so start any of the steps as listed at your leisure.



All of the above have been tested. At the moment we're waiting to see what nvidia can find and if not I'm replacing the psu. There is one point though, it is running 8x and I'm not quite sure why.
m
0
l
a c 272 U Graphics card
February 17, 2010 6:18:04 AM

lemlo said:
All of the above have been tested. At the moment we're waiting to see what nvidia can find and if not I'm replacing the psu. There is one point though, it is running 8x and I'm not quite sure why.

I think your motherboard does 16x + 8x when in SLi not 16x + 16x.
m
0
l
a c 173 U Graphics card
February 17, 2010 11:49:06 AM

Mousemonkey said:
I think your motherboard does 16x + 8x when in SLi not 16x + 16x.



Correct, however that shouldn't become a bottle neck even with 8x+8x sli. Again check your ram timings and test the lower card separately for issues.
m
0
l
February 27, 2010 12:56:17 AM

Yeah it is a 16x 8x sli. The problem was the psu. Thanks for the help guys. Sli has been quite a fun learning experience. All said and done :)  Also btw, those of you looking for top end graphics need not look at dual cards whether it be sli or xfire. I would have been fine with one of those 275's!
m
0
l
!