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Processors

leoberti
Adept I
‎12-16-2020 02:28 PM

AMD Threadripper 3990x drops under base clock

Hi guys,

I have a Threadripper 3990x and under full load (rendering with V-Ray Next) it drops under the base clock (2.9 Ghz).

Im using a Gigabyte Aorus Master TRX40 Rev 1.0 with the latest bios update.  64 gigs of RAM.

Temps are good - in full load it rarely reaches 55' Celsius (cooled with liquid cooler). 

It used to render above 3.0 Ghz (when full load 100%), I just recently noticed that it drops the clock. Happens the same with Corona Renderer as well. 

I noticed that when i activate embree (which in v-ray is impletented by using SSE instructions) this happens. But if i disable embree the render slows down by 20% even if i get over 3.2 Ghz clock speeds all core.

There is no OC in BIOS only the memories are set to XMP profile.

Somehow it doesn't utilize 100% of the cores. It used to be 100% when rendering, not anymore.

I'm attaching a screenshot with HwInfo so you guys can have a look. 

What should I do?

Thank you

AMD3990x.jpg

0 Likes
1 Solution
Thanny
In response to leoberti
Miniboss
‎12-17-2020 03:23 PM

Your processor is working perfectly normally with the stock settings.  You're running a workload which draws more power, meaning the cores have to clock lower.  If you want higher clock speeds, you're going to need to allow the processor to consume more power, which means either doing a fixed manual overclock or turning on PBO.  The latter is a better solution, as it will continue to let the processor ramp higher than the all-core speed on fewer cores with lighter loads, while a manual overclock will not exceed the value you set.

PBO isn't actually overclocking, mind you.  You are increasing the power limits only, and the CPU still decides how high it will clock.  It will just be able to clock higher on all cores under heavy load.  So long as you have sufficient cooling and are using a motherboard with sufficient power delivery (which should be true with all TRX40 boards), enabling PBO will net you more performance under all-core loads with no downside.

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