• Competitor rules

    Please remember that any mention of competitors, hinting at competitors or offering to provide details of competitors will result in an account suspension. The full rules can be found under the 'Terms and Rules' link in the bottom right corner of your screen. Just don't mention competitors in any way, shape or form and you'll be OK.

SLI issues causing 100% CPU usage

ArcticFenrir

ArcticFenrir

ArcticFenrir

Associate
Joined
3 Jan 2014
Posts
19
Location
Hampshire, UK
Okay so I'm having some issues with my SLI setup. I have two KFA2 GTX 770 LTD OC set up in SLI and in some games I'm having some pretty severe issues. It seems that after a while in gaming I start to get some huge visual slowdown spikes, they also seem to affect the CPU, forcing the CPU to spike to 100% usage. This only fixes itself if and when the nvidia driver crashes and I can then use the computer normally. Otherwise I have to reset to do anything.

I've tried using both cards individually and both seem to run fine, I've tried reducing graphical settings in games and that doesn't seem to make a difference. I've even used one as a dedicated physx card with no problems.

The problem I'm sure is a bad SLI connection, I have seen that when the two cards are connected on one side with an SLI bridge the image stutters in game and everything has a weird green and purple hue to it. The other side of the SLI connectors seems to run fine but I still get the slowdown and CPU usage spikes. I've tried a few different SLI bridges and none seem to fix it.

So my question is how can I determine which card is the faulty one? And if it is just a bad SLI connection that's causing my issues? Both cards are from Overclockers and the oldest one was bought in September, the newest in January so I think I can still RMA them if need be.
 
Have you tried a different SLi bridge mate? I have the same issue as you and changed the bridge and works all fine (I have 680s though)

Stelly
 
Run without the bridge, its not needed.

The bridge is simply a PCI-E 1.0 connection between the cards to save Mobo bandwidth, performance will be done a tad but its only to test.
 
Last edited:
Sorry about that, missed that little gem mate...

Just try one at a time, to be honest, I would take them both down myself and let OcUK test them while you are there...

Stelly
 
jh30uk said:
Run without the bridge, is not needed.

The bridge is simply a PCI-E 1.0 connection between the card to save Mobo bandwidth, performance will be done a tad but tis only to test.
Click to expand...

ArcticFenrir said:
Thanks, Ill give that a test and see if I still have issues. Was unaware that you didn't actually need the bridge.
Click to expand...

I thought that you needed the connector to run SLi right??

Stelly
 
ArcticFenrir said:
Thanks, Ill give that a test and see if I still have issues. Was unaware that you didn't actually need the bridge.
Click to expand...

I think long ago it was needed to even work but not for a while.


One of many sources:

"The SLI bridge is used to reduce bandwidth constraints and send data between both graphics cards directly. It is possible to run SLI without using the bridge connector on a pair of low-end to mid-range graphics cards (e.g. 7100GS or 6600GT) with NVIDIA's Forceware drivers 80.XX or later. Since these graphics cards do not use as much bandwidth, data can be relayed through just the chipsets on the motherboard. However, if no SLI bridge is used on two high-end graphics cards, the performance suffers severely as the chipset does not have enough bandwidth."

http://en.wikipedia.org/wiki/Scalable_Link_Interface
 
Last edited:
Stelly said:
Sorry about that, missed that little gem mate...

Just try one at a time, to be honest, I would take them both down myself and let OcUK test them while you are there...

Stelly
Click to expand...
Yeah no worries mate, it happens. I can't take them down to the shop though cause I live nowhere near. My only option is to take it to a local computer shop and have them test it. At a charge of course.


I thought that you needed the connector to run SLi right??

Stelly
Click to expand...

Without the bridge connected the nvidia control panel doesn't give me the option to select SLI.
 
I ran 2x GTX260 216's FTW without one as I had no bridge till I bought one separate (hacked Mobo bios to get SLI license).

Ran slower though.

Suppose Nvidia can change if it works or does not work at any time in new drivers.

Yes would seem it depends on drivers : http://www.overclock.net/t/918741/how-to-enable-sli-without-the-bridge/10

I am not suggesting you run like that ideally, but to check if a bridge is faulty etc.
 
Last edited:
Sory but you do need the bridge. No XDMA stuff going on here.

Sounds like something is causing the issue from software.

Run DDU and completely remove the drivers, reinstall them after the 2 restarts (I have found the latest WHQL drivers to be sweet).

If that doesn't fix the problem, I would look to something like a virus/bit coin miner running.
 
Just to clarify the left side SLI connectors on the cards give me the visual errors. The right side seems to work fine but after a while I just get the CPU overload in certain games. But even on low settings I still get those issues. But then those same games can run perfectly fine on high settings on a single card.
 
As I said at times in past drivers you did not need the bridge, you can find many sources for that fact.

I am not just talking about my hacked Intel Maximus formula II doing unofficial SLI.

Sorry if its no help now on current drivers but I did not know.
 
Okay so uninstalled video drivers and now I'm running a fresh install. Gonna do some tests. If this doesn't work I take it my only other option is to take it to a shop and get it tested? Any other advice would be appreciated.
 
Okay so everything seemed to be working okay last night. I spent a few hours playing Warframe which is one of the games that causes me issues and it ran fine. However today when playing Thief after a little over an hour of playing it starts to lock up. Any other suggestions on what might be causing this issue?
 
When I was using i5 2500k with 2x 7950s I also had 100% CPU usage and low gpu usage. Switched to i7 2600k and not had it happen since.

I5 is great for single gpu but was you start adding in sli or crossfire I don't think it's good enough.

This from my own experience.

You could also try running cpu at stock and test to rule out bad overclock.
 
shankly1985 said:
When I was using i5 2500k with 2x 7950s I also had 100% CPU usage and low gpu usage. Switched to i7 2600k and not had it happen since.

I5 is great for single gpu but was you start adding in sli or crossfire I don't think it's good enough.

This from my own experience.
Click to expand...

Yep, exactly the same here.
 
rather than gpus what game are you testing it on, if its just happening on 1 (BugField4?) then it could be the memory leak I experienced.. caused 100% cpu and visual slowdowns like you said.

Then it started happening on bioshock, planetside 2 and a few others.
THE ONLY FIX I have found is to run the gpus at 2.0 not 3.0 (PCI-E speed in bios) .. why it works now I can't tell you but let me know if that helps :)

also the difference in performance between 3.0 and 2.0 is less than 1% so no issues with lost performance, stable as a rock now

As others have mentioned an i7 helps (Extra threads) and to be fair that will be my next upgrade but as things stand right now I'm very happy.
 
You must log in or register to reply here.
Back
Top Bottom