CPU TDP throttling when run with GPU on full load

[Battlebared]

I'm using a 330W power supply, but that is simply not enough whenever my 2x 980m sli is running under full load, such as when I play a game like Rainbow Six Siege. The CPU will automatically downclock itself to around 1500Mhz with a package power of around 28W to make room for the GPU. This can be seen in any somewhat GPU-heavy game, and my framerate will drop from 90 to around 30FPS because of my CPU.

My GPU is untouched and my CPU is overclocked to 4.1Ghz in all cores. However, even removing the overclock my CPU still has TDP throttles until I close my game, which it will shoot back up to 4Ghz.

Is there a way to fix this? Do I need a larger power brick to deliver more power, or could I tweak something in the BIOS to resolve the issue?

 

[mantadog]

first of all it would help if you could post your full specification, I can see from your post history you were thinking about a octane machine but you had that specced up with a single desktop class 980 and not the dual 980m's you list in the OP.

Given your mention of an overclock in a laptop chassis you have me slightly worried, a 100Mhz overclock isn't much (assuming you wnt with the i7 from the previous post) but a desktop class cpu in a laptop chassis is going to be pushing it already.

My feeling is you are having thermal throttling and nothing to do with the power that can be supplied by the PSU, but without more info its hard to tell. It could just be a faulty PSU but I don't see it manifesting as the symptoms you describe.

 

[Battlebared]

I have:
i7 6700K
2x 980m running in SLI
32GB 2133Mhz RAM (Hyper X Impact)
512GB SSD
2TB HDD 5400RPM
Vortex V Elite Chassis (Clevo P870DM-G)

I'm positive that it's certainly not thermal throttling. My CPU runs at around 80C during most games, with CPU benchmarks causing it to run at 86C. GPU stays at 78C under maximum load. The problem is, the CPU will automatically underclock itself as it starts to run at max load, and the problem persists even when the CPU temp is down to 70C.

 

[Oussebon]

I believe the 980M has a TDP of ~125W, while the 6700k apparently has a power consumption of 80-100W under heavy load: http://www.tomshardware.co.uk/skylake-intel-core-i7-6700k-core-i5-6600k,review-33276-11.html

330W does sound a bit slender, but it seems to have been what was supplied as standard with the Vortex V Elite: https://www.pcspecialist.co.uk/foru...e-Spec-Ordered-can-t-wait!&highlight=vortex+V
And you were apparently using it before without having this issue.

Is the 330W power supply you have the one that was originally supplied with the laptop, or is it a replacement perhaps of a different model?

I don't have any solutions to suggest. All that springs to mind would be reducing the load on the GPUs by capping the FPS with Vsync or Nvidia Inspector, which I believe can be done.

That Tom's Hardware review showed the i5 6600k to have 14W lower power consumption in the gaming they did. You could try disabling the hyperthreading on the 6700k to see if that cuts power draw enough to stop it downclocking.

 

[mantadog]

you could try underclocking the cpu by a small amount and seeing if you can figure out exactly at what point you stop seeing the fps drops.

if you can be certain its not thermal throttling then it could be the PSU has stopped being able to supply quite as much power as it once did, as they do degrade as they age. so might be worth trying to get a replacement.