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GTX 460 SLI, Slow Performance & Weird Interference

RiGoRmOrTiS

RiGoRmOrTiS

RiGoRmOrTiS

Associate
Joined
7 Dec 2008
Posts
79
Location
Newcastle, UK
System Spec:

Windows 7 Professional x64
Intel Corei7 920 2.6Ghz (Stock Speed)
6GB DDR3 (1600Mhz) RAM
Asus P6T Deluxe X58 Motherboard
2 x Western Digital Black 256GB Drives in Striping RAID
Zalman Ultra Quiet Dual Heatpipe Cooled 850w PSU

Old Graphics Card: ATI Radeon 4870 1GB
New SLI Setup: 2 x Geforce GTX 460 1GB (SLI Setup)

Nvidia Drivers: 258.96

Just swapped out my old Radeon 4870 with 2 GTX 460's after reading all the rave reviews of how well these cards scale with SLI; apparently beating out a single GTX480.

The Problem!

However I'm having nothing but problems. Any games I play with SLI enabled see a significant drop in performance. The games run slower than my old 4870 and considerably slower than a single GTX 460.

The two main tests (that support SLI) that I've used are Starcraft 2 and Crysis.

If this wasn't bad enough; I have another problem. Whenever running games full screen using SLI I get a strange blue flashing pattern; kind of like visual interference.

Here is a link to a video I made of the problem:
http://www.youtube.com/watch?v=vhbYD_w_Cog

However if I run either card individually I don't get this problem and my performance returns to what you would expect from a single GTX 460. The fact that each card runs on its own without issue implies (to me) that neither card is faulty?

Another thing I've noticed; if I remove the SLI bridge connector; the strange blue pattern disappears and everything looks fine; however I still have the bad performance issues where two 460's are slower than one.

Historical Issue

I will also document one other symptom that my system has always had since day 1; when I originally built it. Since I feel it may have some relation to the problem.

Sometimes I can hear a strange squeaking; squealing noise (sounds somewhat electrical) when scrolling up and down graphic intensive websites; watching "bink" format videos (such as the Crysis intro video) or heavily animated flash videos. On more rare occasions I can hear it when my HDD's are accessing heavily. I "think" the noise is coming from my PSU; but even with my head in the case sometimes it sounds like its coming from the motherboard. Originally I thought it might be the Radeon graphics card since the noise seems to appear during certain graphical tasks; however the sound still remains with the new Nvidia cards installed.

Is it possible my PSU is faulty? and its not providing enough power for both GTX 460's? I personally don't think slower performance would be an indicator of a lack of power to the card; I would actually expect system locks; bluee screens; crashes or re-boots...

also why does the blue flickering pattern disappear when I remove the SLI bridge (SLI continues to function; but slower than a single 460). If its a faulty SLI bridge surely I would still get better performance on two cards (even when the bridge is removed?).

I'm at my wits end; any help would be seriously appreciated.
 
Welcome, that flashing problem youre having looks similar to a problem i had lasy tear with SLI 8800GTX's. I fixed it by swapping the SLI bridge :)
 
is it normal for ther performance to suffer as well (with a faultly SLI bridge connector and when the connector is also absent).

Because starcraft 2's in-engine cut scenes are hitting new lows when I have SLI enabled. my single 4870 performed better >_< but when I disable SLI and run one 460; its faster than my old 4870 or 2 460's together.
 
Make sure your not forcing SLI rendering mode in the 3D settings part of the nVidia control panel - while this is typical symptoms of a faulty SLI bridge, I would be completely unsuprised to find its due to the motherboard.
 
Rroff said:
Make sure your not forcing SLI rendering mode in the 3D settings part of the nVidia control panel - while this is typical symptoms of a faulty SLI bridge, I would be completely unsuprised to find its due to the motherboard.
Click to expand...

Faulty motherboard causing the performance issues you mean? is it possible its the motherboard making those strange noises as well?

Like I said, performance remains equally poor with and without the SLI bridge; the main difference is that without the bridge the visual problem goes away.

thanks for the speedy replies by the way :)
 
RavenXXX2 said:
Yeah but 2.6Ghz for an SLI setup is bottlenecking your cards IMO.
Click to expand...

Is there some CPU requirements to run SLI that I'm not aware of? I assumed the cards and the motherboard handle all the interaction between SLI; if you don't mean this then I'm confused by your point. I'm not aware of any games where they perform worse under SLI than a single card because of your CPU.

Rroff said:
What is the SLI rendering mode set to in the 3D Settings part of the nVidia control panel?
Click to expand...

it's set to NVIDIA recommended.
 
Running an i7 at stock won't get the best out of your GPU setup - but neither would it cause the slowdowns your seeing.

Are you sure your previous ATI drivers are cleanly removed?
 
Rroff said:
Running an i7 at stock won't get the best out of your GPU setup - but neither would it cause the slowdowns your seeing.

Are you sure your previous ATI drivers are cleanly removed?
Click to expand...

Yeah I did a full uninstall and re-boot before I finally powered down to install the GTX 460's. then upon boot-up I downloaded the latest nvidia drivers and installed them. all drivers settings are stock apart for enabling SLI.

All system drivers are the latest releases and its a legal, fully patched Windows 7 install.

I will just make a note however; I've just ran the Final Fantasy XIV benchmark and with one GTX460 I only got a score of 2500; which is the same as my old ATI 4870; when I enabled SLI, I only got 3500; however it had some slow signifcant slowdown in certain parts; I'm pretty sure both these scores are far lower than they should be for a GTX460.


as a side note; are the original release i7 920 locked? because I've never been able to enabled overclocking in my BIOS.
 
I would definitely up the clock on that i7. Take to 4GHz where it belongs. As for the graphics issues, check the SLI bridge, and also check all old ATi drivers are gone. If that doesn't fix it, check both PCI slot on your mobo. As for removing the bridge, surely SLI can't still be in effect, as you are removing the communcation link for both the cards?
 
madindehead said:
I would definitely up the clock on that i7. Take to 4GHz where it belongs. As for the graphics issues, check the SLI bridge, and also check all old ATi drivers are gone. If that doesn't fix it, check both PCI slot on your mobo. As for removing the bridge, surely SLI can't still be in effect, as you are removing the communcation link for both the cards?
Click to expand...

I've been informed that it'll throw it all across the system bus and that SLI bridge is just providing an additional 1GB link for data? doesnt seem to improve performance when I attach it; just gives me that strange blue flickering. SLI indicator overlay shows me SLI is in operation with and without it..... I've noticed that when I get the major slowdown during SLI the indicator retreats into a very small line at the centre of the box; rather than filling it top to bottom.

and I've tried to overclock but my motherboard doesnt want to let me; I'm assuming my i7 is locked? unless i'm mistaken.
 
Last edited:
Ok. Maybe it is a faulty SLI bridge. Or a faulty PCI slot? Have you tested each card in each slot?

As for overclocking the i7, the multiplier is locked at 21 (normally use 20) on the 920, but the BCLK isn't. Overclock it using that.
 
madindehead said:
Ok. Maybe it is a faulty SLI bridge. Or a faulty PCI slot? Have you tested each card in each slot?
Click to expand...

I get the same performance running single GPU modes from both PCI-E slots.

madindehead said:
As for overclocking the i7, the multiplier is locked at 21 (normally use 20) on the 920, but the BCLK isn't. Overclock it using that.
Click to expand...

I'll give that a shot now.
 
SLI still works without the bridge - performance loss is generally minimal - mostly just a hit on load times.

Try setting the PCI-e bus to 101 (or 99 or 102) in the BIOS as well.
 
Rroff said:
SLI still works without the bridge - performance loss is generally minimal - mostly just a hit on load times.

Try setting the PCI-e bus to 101 (or 99 or 102) in the BIOS as well.
Click to expand...

Do you mean the frequency? I've just overclocked to 3.8Ghz (3988.9 according to CPU-Z) so that'll suffice. Temperature was hovering around 50c in BIOS; going to monitor with asus probe and see how it goes; I fitted a Tru (something or other) cooler to do this back when I built the system; but those options were greyed out then ;) but now they ain't.

Do you think changing the PCI-e bus will help with my techincal issues?
 
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