Question 3080 Ti and PerCap question

[Paul Anderegg]

Playing around trying to optimize my MSI afterburner settings a bit more. Was running stock memory speed, have since upped that +500 (safe), and have moved on to undervolting. Temp power balance for my card seems to be in the area of 0.843v 1950MHz 350watts 65c in Heaven.

My question comes as to the best way to determine how to reach these magical numbers. Depending on how far down I pull the curve down prior to pulling it up at 0.843v, changes the PerfCap results. Some settings result in no PerfCap, some PerfCap all the time even 50 watts below TDP, some 50/50 PerfCap power, and a few weird one Vrel etc. None of them crash, all maintain an average 1950MHz core clock and same temps across a Heaven benchmark run following 10 minute Heaven "preheat".

Given the identical numbers for what i am looking at, can someone explain which is the preferred results for PerfCap, and how best to get the most boost? I m currently running -150 clock, then curve pulling up +275 to 1935MHz at 0.843v. Setting core to -250 and pulling up to 1920 in the curve produces the same results but different PerfCap readings, so confusion as to the best stable experience for something like VR that would max out the GPU.

Paul

 

[JWNoctis]

Two things come to mind:

First, why are you doing this? Is your framerate unacceptably low or unstable? I understand that Ampere-generation chips are pretty efficient at lower TDP, but the performance/power curve flattens out very quickly. A framerate cap with adaptive sync should be a better cure for unstable framerate, and would save you a bunch on your power bill.

Second, Unigine Heaven benchmark is very old, and probably will not load a modern GPU properly at any resolution or framerate.

 

[Paul Anderegg]

To the first query, my game of choice is Microsoft Flight Simulator 2d and VR. MSFS is single threaded for the most part, requires that single core to be as fast as possible and demands a lot of L3 cache on the CPU. For GPU, as the sim is basically slamming against the limits of either the main thread or the GPU limits (especially in VR) you live with the damn thing having stuttery and glitchy framerates unless you vsync it to something pathetic like 30Hz. I don't have a VRR capable TV. These "microstutters" really take you out of the immersive experience, so just looking to optimize as much as possible to mitigate them within reason.

By optimize I mean if this were a car I would be making sure the tires are correctly inflated cold, spark plugs gapped properly, fuel injectors and MAF clean and providing proper air fuel mixture etc.

For the second query, Heaven is enough to heat/stress test while prepping an overclock/undervolt. I typically use Superposition benchmark to crash test afterwards, as it is more sensitive to issues. My 3080 Ti has a low 350 watt power limit, which is really easy to peg in Heaven even at 0.843v.

Paul

 

[hotaru.hino]

PerfCap is simply a reason why the card won't boost any further. As for the reasons:

• Pwr: Hit the power limit.
• VRel: Hit the soft voltage limit defined by the V-F curve
• VOp: Hit the maximum voltage limit
• Thrm: Hit the thermal limit
• Util: Not enough is going on to need to boost

You can try and raise say the power limit or increase the voltage, but there's nothing you can do if you keep hitting them. There's no "preferred" result, and it's not an error per se. It's simply telling you why the GPU won't boost further.

 

[Paul Anderegg]

PerfCap is simply a reason why the card won't boost any further. As for the reasons:

• Pwr: Hit the power limit.
• VRel: Hit the soft voltage limit defined by the V-F curve
• VOp: Hit the maximum voltage limit
• Thrm: Hit the thermal limit
• Util: Not enough is going on to need to boost

You can try and raise say the power limit or increase the voltage, but there's nothing you can do if you keep hitting them. There's no "preferred" result, and it's not an error per se. It's simply telling you why the GPU won't boost further.

Thank you. I was keen o make sure that the PerfCap indicators were not resulting in any throttling of the core clock...the pwr PerfCap indicators while well below TDP was what was really confusing me, and I was not sure if this meant I could juggle the settings until i got a consistent PerfCap pwr while maintaining fixed core boost clock.

Paul

 

[hotaru.hino]

Thank you. I was keen o make sure that the PerfCap indicators were not resulting in any throttling of the core clock...the pwr PerfCap indicators while well below TDP was what was really confusing me, and I was not sure if this meant I could juggle the settings until i got a consistent PerfCap pwr while maintaining fixed core boost clock.

Paul

https://www.techpowerup.com/forums/...fcap-pwr-below-90-pf-tdp.287299/#post-4617104

That explains why you can get a power limit hit even though the TDP is not reporting 100%. The tl;dr though is there are multiple power rails on the video card. If any of them hit or report a power limit, it triggers the perfcap reason.