[PSA] GTX 970 VRAM Allocation Problem

[EChondo]

Hey everyone, I haven't seen this posted here yet and I've recently seen this and read up on it a bit, so I thought I'd give everyone a heads up that some/most/all GTX 970's might have a VRAM allocation bug that degrades performance when more than 3500MB of VRAM is being used. We do not know if this effects ALL 970's, but there have been reports popping up about this issue.
 
From Reddit: http://www.reddit.com/r/pcgaming/comments/2s2968/gtx970_memoryvram_allocation_bug/

Crossposted to /r/Hardware on Reddit: http://www.reddit.com/r/hardware/comments/2s333r/gtx_970_vram_allocation_bug_xpost_rpcgaming/

A few weeks ago, someone posted an issue with the 970 with low GPU usage. Not many people have this issue, atleast those I've come across, but the following might be reproducible for many people.

Here is a Guru3D post on the topic.

Basically, in a scene where GTX970 allocates 3500, the 980 allocates 4000mb. It is possible for a 970 to allocate 4000mb VRAM but only in severely extreme scenarios(Like 5k res with MSAA). For instance, Shadow of Mordor on ultra textures at 1080p seems to hover around 3600mb VRAM, Skyrim doesn't want to go beyond 3570MB, and hitting 4k only makes it 3580MB. A 980 allocates 4000MB in all these scenarios. Far Cry 4 and Watch Dogs are also around 3600mb on the GTX970 where in the same scene the GTX980 will allocate 4000mb.

Going beyond 3.5GB vram usage in games like Hitman Absolution, Call of Duty Advanced Warfare severely degrades the performance, as if the last 512mb is actually being swapped from the RAM.

Memory Burner seems to run at 3979mb fine, however its failing for a few 970 users once it loads beyond 3000mb.

If you have a GTX970, and are running across some of the issues like in Skyrim, I'd advice to read through the thread. It may not exactly be a driver issue because ENB can override driver memory management, which leads to the conclusion that either these cards are 224bit under the hood, or they are built this way. Or it could be that 2 ram chips are actually 256mb, and the last 512mb is shared from system RAM. These are only theories which are hopefully debunked and nvidia comes up with an explanation.

Having a 3.5Gb card isn't exactly bad, but selling it as a 4GB card is what pisses me off.

Once again, the GTX970 allocates 3500mb in the scene where the GTX980 allocates 4000mb.

Watch Dogs GTX970

Watch Dogs GTX980

Small update, Guru3D user aufkrawall2 uploaded a video to zippyshare showcasing Hitman Absolution with this issue. His post:
 

Once more than 3.5GB gets allocated, there is a huge frametime spike. The same scene can be tested to get reproducible results. In 4k, memory usage stays below 3.5GB and there is no extreme spike. But in 5k (4x DSR with 1440p), at the same scene, there is a huge fps drop once the game wants to allocate 2-300MB at once and burst the 3.5GB. It happens in the tutorial mission when encountering the tennis field. With older driver (344.11 instead of 347.09), memory usage is lower, but you can enable MSAA to get high VRAM usage and thus be able to reproduce by 100%.

 

Now, I'm not pointing fingers, but this might be something for 970 users to look out for and test. 

[TheKDub]

Maybe I should wait to buy my 970 then....

 

Or I could just go ahead and get it anyways, I only plan to game on a single 1080p monitor for now, may go for surround or 1440p in the future.

[AlexGoesHigh]

driver bug?

[LemonSpice]

driver bug?

hopfully not firmware or hardware

[Apple_II]

I really hope nvidia can get back to somebody regarding the issue. Is there a way to reach nvidia regarding the issue?

[sgloux3470]

Quite frankly this will only negatively affect performance if you're running MSAA on 4K.

I'm amazed reviews didn't notice this.

[EChondo]

driver bug?

After some more reading around the people reporting this issue have problems with DirectX games while OpenGL isn't an issue.

 

It's entirely possible this is a driver issue.

[Timmy-P]

I really hope nvidia can get back to somebody regarding the issue. Is there a way to reach nvidia regarding the issue?

Flood the NVIDIA forums and support email inbox.

[smittywits]

Oh, well. That's unfortunate. I had intended to purchase two 970s and SLI them for use in a video production rig. I guess I'll have to wait for a bit before I make my purchases. Thanks for posting this, you probably saved me a lot of hassle and possibly a fair amount of money too.