GSync + SLI + Shadowplay = 1/2 FPS [even when not recording]

[GhostOrange]

I posted this in another thread:

I am creating a new thread for this issue (as my first thread on the BB forums!!) but I wanted to post here, too, because I think it's relevant.

Prior to installing G-Sync, I was running 2x SLI GTX 770 4GB and was getting around 145-150FPS in BF4. I was able to run Shadowplay and record on High with ~5FPS drop when it was running.

Now that I've installed G-Sync on the *exact* same system, when Shadowplay is enabled (note: NOT even running) it cuts my FPS down to 80FPS. This is a massive hit.

Since there are many users on this thread using similar setups I'm wondering if anyone else has experienced this?

Note that I have tried 5 different drivers, GF Experience 1.8, 1.8.1 and 1.8.2 with the exact same results. I have also tried OBS, which works well, but still takes about a 30FPS hit. I've seen similar issues in other games, too, though not cutting FPS in half.

The odd thing to me is that w/out Shadowplay I'm actually getting around 10-15FPS higher avg FPS w/G-Sync than without.

I'm looking for any input. I'll post my system specs below.

Things I've tried:
1) Drivers: 331.65-present. 331.65 is not an option because it doesn't support G-Sync
2) Checking drive, CPU and network usage for issues. Nothing is any different than before. In fact, the GPU usage on both cards hovers right around 65%.
3) I have 2 SSDs and a Seagate SSHD. I have a Samsung 840 pro for Windows, 840 EVO for games and the SSHD is everything else. It doesn't matter which drive SP writes to, performance is the same.
4) I've tried GeForce Experience 1.8, 1.8.1, 1.8.2. All the same.
5) I've tried another monitor without G-sync. If the G-sync driver is installed/initialized, the problem persists.
6) Turning G-Sync off does nothing to help.
7) Disabling SLI does nothing to help and the performance is proportionally the same; max FPS is lowered to about 65, drops as low as 25.
8) I've tried every damn combination of settings in Nvidia Inspector. Nothing.
9) I've added the Shadowplay exe files to the BF4 profile in Nvidia Inspector. No improvement.
10) I've recently done a fresh install of Win 8.1. No improvement.

System specs:

Win 8.1 all updates
ASRock Z77 Extreme 4
i5 3570k @4.5GHz (perfect voltage; no WHEA errors, etc)
2x Gigabyte GTX 770 4GB in SLI
Asus VG248QE w/G-Sync
8GB GSkill 1866 DDR3 9-10-9-28 @stock
Samsung 840 Pro 128GB
Samsung 840 EVO 128GB
Seagate 1TB SSHD Hybrid w/8GB NAND

I have no temp issues, nothing ever gets above 70C. I have no voltage, BSOD, or other issues. Any suggestions welcome.

(PS - This is my first post on the BB forums. Give me a cookie.)

[Chief Blur Buster]

That is strange -- if I am reading this correctly:
Having ShadowPlay installed but not running, gives you a huge framerate hit?

I'll notify ManuelG about this, because it is relevant to their driver development.

[GhostOrange]

That is strange -- if I am reading this correctly:
Having ShadowPlay installed but not running, gives you a huge framerate hit?

I'll notify ManuelG about this, because it is relevant to their driver development.

To be clear: installed, just fine. Once it's turned on, that is not actually recording, but activated so that you can use Alt+F9 to record, there is about a 40FPS hit to my normal 148FPS in BF4, and about a 15FPS hit in ACIV, just as an example.

Once it's turned on, BF4 drops another 20-30FPS. Basically, while Shadowplay is active my SLI setup acts as though I only have one card. With SLI off, it's proportionally equivalent. To be clear, though, Afterburner still shows equal activity on both cards, so it's not as though SLI is suddenly shutting off.

I've also forced SLI on via Nvidia Inspector, but there's no change.

If I disable G-Sync in the driver settings, the problem still persists. It appears as though the G-Sync driver itself conflicts with Shadowplay because even when then attached to a non-G-Sync monitor the results are the same.

My best guess is that something about the driver and the VRR conflicts with Shadowplay's CBR sampling, resulting in a large buffer before a frame is sampled; possibly that Shadowplay doesn't know when to sample a frame and keeps buffering waiting to sample, thus bogging down the GPU and/or VRAM.

The only thing is, I haven't recorded any outrageous VRAM or GPU usage w/Afterburner to prove this. I'm going to attempt to roll back to 331.65 (non-G-Sync) and see if the issue persists as this is the only situation I haven't fully tested.

I'm actually wondering if this is a firmware related issue tied in w/the G-Sync module; somehow the communication between the G-Sync unit and the card is negatively affected when Shadowplay is enabled. It's the only explanation other than a driver affecting it that would explain why it happens even when G-Sync is disabled.

**EDIT**
It just dawned on me that because the G-Sync hardware must know the frame rate and access a frame buffer to coordinate refresh rate with frame rate, this means that it's accessing the frame buffer on a hardware level to "count frames" and adjust accordingly. Shadowplay must ALSO be accessing a frame buffer to sample frames, but via an API. The G-Sync *driver* must also access the frame buffer via API in order to communicate back and forth w/the monitor hardware. If both Shadowplay and G-Sync are accessing the same buffer at the same time, this would explain why FPS performance is cut in half.

The obvious solution would be to increase the frame buffer size, or if possible, have the two access separate frame buffer addresses. It should be cached separately for Shadowplay.

Just a thought.

[GhostOrange]

Any response from ManualG?

[Chief Blur Buster]

Just heard back. They are aware and have recorded this issue, as they got one other report. No word yet on when the fix is. I will let Manuel update when the time is ready.

[GhostOrange]

Just heard back. They are aware and have recorded this issue, as they got one other report. No word yet on when the fix is. I will let Manuel update when the time is ready.

Awesome. Thanks for the response. Better than being completely ignored on the GeForce forums.

[sharknice]

Could it be your hard drive? I'm guessing Shadowplay has to temporarily store the last X minutes of gameplay video on your hard drive even if you don't save it. How is your hard drive performance. It could be bad due to fragmentation or being too full. Are other things using your hard drive like torrents?

[Di9i7a1H8]

I had the same issue with sli enabled and shadowplay on, I would get about the same performance as using 1 card. I sent feedback in Geforce Experience, but I only discovered today that it had anything to do with G-sync. I just got the idea today to unplug my g-sync monitor and try it with a different one and it worked fine. I originally thought that shadowplay just didn't support sli, although I do remember trying it when shadowplay first came out and it worked fine back then too. I don't record gameplay much so I didn't really care. It is nice to know that they are aware of the issue now tho.

[GhostOrange]

Could it be your hard drive? I'm guessing Shadowplay has to temporarily store the last X minutes of gameplay video on your hard drive even if you don't save it. How is your hard drive performance. It could be bad due to fragmentation or being too full. Are other things using your hard drive like torrents?

No. I have no other major background processes running, and I don't torrent, or use other network/internet programs especially when playing online multiplayer games, lol.

Also, my games are on their own Samsung 840 EVO SSD, Shadowplay is on the C: drive, of course, on a Samsung 840 Pro and it's writing to a Seagate SSHD 1TB hybrid, so it's not my hard drives being bogged down, and it worked fine prior to the upgrade, so I would have seen this then.

[GhostOrange]

I posted this on the GeForce forums a few minutes ago, but as most of the users seem to be 15yr olds who are only interested in blaming Nvidia rather than troubleshooting, I thought it might be useful to post here:

And here's how I know it's related to G-Sync:

1) Driver 331.82 (WHQL version of 331.65 beta) was the first to add G-sync support. 331.65 will not even recognize that you have G-sync.

2) For most users, the G-sync driver doesn't initialize until you connect a G-sync device, but some had reported seeing G-Sync as an option under the V-sync options. I didn't until I installed G-Sync.

3) I NEVER had this issue prior to installing G-Sync, but DID have SLI. I was on 332.x drivers and still had awesome SP performance.

4) The DAY I installed G-Sync, as soon as I connected it, Shadowplay went to crap on first use.

5) The G-sync option magically appeared in my driver options w/out a driver reinstall, as it should.

6) Shadowplay had to be reinitialized after connecting G-Sync.

7) Rolling back to 331.65 doesn't fix this issue - even though G-Sync isn't available.

This indicates an issue on the firmware level that affects the card's performance. How could completely removing a driver and switching back to a working driver suddenly have the same effect as the bad driver? It's impossible unless it's a firmware switch.

My guess is one of two things are going on, or both:

a) G-Sync triggers a hardware switch when connected via firmware from the G-sync board that isn't driver-controlled. (I'm an EE, so don't argue - this is entirely possible)

b) Coincidentally, the DisplayPort output has always been affected by this bug and it wasn't discovered by me or other now-G-Sync users prior to G-Sync because we used DVI or HDMI which use a different type of signal.

If this is true, non-G-Sync SLI users experiencing this issue should be able to switch to DVI or HDMI and see the issue resolve itself. It'd be great if one of you guys could test this.

Alternatively, as it may be tied to drivers after 331.65, it might be smart to roll back to those first.