SLI difficulties...

[railven]

Rig in Sig, 1440p monitor.

I finally decided to finish Bioshock: Infinite and using the system in sig, I must say, it was a terrible experience. I still finished the game, just not sure what is wrong with my system.

Ailments: in SLI I get weird discoloration during hitching. Changing in game Bioshock settings did not prevent the hitching, game would be fine 60 FPS, then suddenly 2-3 second hitching, discoloration (only way to explain it is like compression artifacting on a bad youtube video), and some times even 2-3 second complete system freezes.

At first I thought my SLI 660 Ti setup couldn't handle Custom_Ultra @ 1440p, so tried Preset_ultra, then @ 1080p, then Preset_Very_High and Preset_High both @ 1080p, still had the hitching and discoloration (note: there was always discoloration during the loading screens.)

Finished Bioshock, loaded up SKyrim, see the same discoloration during the Bethesda Logo right at the start and during loading screens. In game, get the hitching with discoloration (something that didn't happen in Bioshock.)

Already tried:
re-installing drivers
Using latest Beta/WHQL
Testing solo card (both seem to work, of course struggle for 1440p)

Going to test resitting the cards, possibly damaged SLI bridge? Tried both with GPUs OC'ed and Stock, same issues.

Wondering if it's a VRAM issue? The discoloration? Anyone ever experience such an issue?

TL;DR:
Getting weird discoloration and hitching when using SLI with my two 660 Tis, wondering if one is damaged or I'm missing a troubleshooting step.

EDIT: Also, little info on the cards:
EVGA GTX 660 Ti, was RMA'd first one I had died after 3 days of installation. Not sure if EVGA sent me a new card, or just "fixed" it.

Second card was bought refurbished at local Microcenter, Nvidia brand.

Didn't have an issues running a few benchmarks with each card individually, but didn't stress test since I wasn't going to OC them very much, highest I ever OC'ed was +100 core and +400 memory, ran fine, BSOD'd once.

 

[railven]

Example of hitching during Bioshock, just remembered I grab some screen shots to show someone. There is no discoloration here, I'll try to grab a screenshot of SKyrim that shows discoloration with the hitching.

Stuttering came back, again at specific areas. I took some screen grabs to show how bad it is, this specific area I didn't move just panned around and you can see how my FPS fluctuates, more importantly neither GPU is taxed over 40%.

 

[AntonioHG]

I had a damaged SLI bridge and I got weird color banding. Try returning your CPU to default too.

 

[railven]

I had a damaged SLI bridge and I got weird color banding. Try returning your CPU to default too.

Ah, forgot to mention that, CPU was restored to stock. While trying to fix the Bioshock issue (and trying all the *.ini tweaks I came across) I read that early Bioshock had issues with Intel Hyperthreading, so disabled that and set CPU to stock in the process.


Also, color banding would be one way to describe it. Hopefully it's a simple bridge issue. Will tinker with that tonight once I get home.

 

[digitaldurandal]

Have you tried running your PC completely stock? Have you noticed this in any other games? Did you have an AMD card previously in the machine?

 

[Termie]

Remember that the 660 Ti has a narrow 192-bit memory bus. Only 1.5GB of VRAM works at full speed, and the other 500MB, when in use, can compromise speed. I notice in all three screenshots you are above 1.5GB. This could be the issue. Because you are clearly not over the 2GB limit, it's not a standard out of VRAM problem.

Read about the 660 Ti's memory architecture here: http://www.anandtech.com/show/6159/the-geforce-gtx-660-ti-review/2

Of course, the color banding is distinct, but not necessarily caused by the same problem - that surely could be an SLI bridge issue.

 

[railven]

Have you tried running your PC completely stock? Have you noticed this in any other games? Did you have an AMD card previously in the machine?

Yes, completely stock. Yes, noticed it in Skyrim now. Yes, had CFX 7970's before, but PC reformatted after switching to GTX 660 Tis.

Remember that the 660 Ti has a narrow 192-bit memory bus. Only 1.5GB of VRAM works at full speed, and the other 500MB, when in use, can compromise speed. I notice in all three screenshots you are above 1.5GB. This could be the issue. Because you are clearly not over the 2GB limit, it's not a standard out of VRAM problem.

Read about the 660 Ti's memory architecture here: http://www.anandtech.com/show/6159/the-geforce-gtx-660-ti-review/2

Of course, the color banding is distinct, but not necessarily caused by the same problem - that surely could be an SLI bridge issue.

That's food for thought. I recall running Bioshock stock (no *.ini tweaks) and the Memory was <1.2GB, but I still had the terrible hitching.

And the color banding/discoloration issue is for Bioshock is during a loading screen, the memory hasn't even loaded.

One thing I'm remembering is that the flickering/discoloration would lessen as the FPS meter got closer to 60. For Skyrim, the parts where it happens I'm always below 60 FPS (Bethesda logo/Loading screens @ 30 FPS), during gameplay the game hitches, drops frames, notice the discoloration as the FPS returns to 60.

Will read that article, thanks for the heads up.

 

[railven]

Well crap, does that asymmetrical setup of there have any real world performance issues (ie a benchmark showing how going over 1.5GBs of memory usage shows a negative performance impact?)

Guess regret is kicking in even more for selling those 7970s BEFORE the Bitmining craze. Ah hindsight, you SOB!

The issues I've experienced remind me clearly of a memory limit (the hitching.) The GPUs aren't even fully loaded, but it almost felt like the system was hitting a memory point and had to flush/recache or whatever the correct terminology would be. Monitoring the CPU via HWMonitor showed no erratic dips/spikes, and monitoring the GPU through MSI also showed no flux in load, just - random hitching.

Perhaps I should keep an eye on VRAM load?

 

[railven]

Hmmm...perhaps the better question is: can SLI GTX 660 Ti even handle 1440p?

 

[monkeydelmagico]

I think 660ti's should be able to handle it well.

swap card positions just for lol's

Clean windows install?

 

[railven]

I think 660ti's should be able to handle it well.

swap card positions just for lol's

Was going to swap them, but forgot D:

Clean windows install?

Yes, when both cards went in, got a Clean Install of Windows.



It seems my issue is resolved, for now. I took out both cards, gave them a nice cleaning (was gonna re-TIM, but got lazy :\) and stupidly put them back in the exact same slots. Oh well. Put bridge on the first notch (closest to back of the case) versus the second notch. Read on the interwebs that it didn't matter.

Driver Sweeper, needed it couldn't uninstall PhysX through it's own installer - woof so much Bloatware when using the stupid auto-updater from NV Experience, my own fault. Reset my Bioshock *.ini to address only 1024MBs of VRAM instead of 1536.

No hitching during the ending events. No discoloration during any of the loading screens. Was able to do Custom_Ultra @1440p 90% locked at 60 FPS, few dips into the mid 50s.

Loaded up Skyrim. No discoloration during the Bethesda logo. No hitching + discoloration during the intro level. I even loaded up a few HD texture mods and an ENB profile with a few dips to the mid 50s @ 1440p.

So far so good. Glad it isn't a bigger issue.

Thanks everyone for the suggestions.

 

[f1sherman]

reseating HW/cables... mother of all fixes