X99 (Xeon) CPU Throttling/Frequency Problem

[paradigital]

Hi guys, hope one of you can help, or point me in the right direction. I've just finished building a rig based on a Gigabyte GA-X99-SOC Force motherboard, coupled to a Xeon E5-1620 v3, and 32GB of Kingston HyperX Predator (2666) RAM. For the sake of "completeness" I'm watercooled using an EK Supreme, 2x EK CoolStream 360 radiators, a XSPC Photon 270/D5 combo and I've also got my 1070 in the loop using a Heatkiller IV full-block.

Now, the problem that I'm having appears to be one of the CPU not running at full speed, or indeed anything even approaching full speed. I'm not sure if it's something to do with Turbo or similar, but the CPU will not run at anything other than 1.2GHz (100x12), and in Windows no amount of loading up the CPU does anything other than keep the vcore at 0.7v and the frequency at 100x12. When the machine boots into the BIOS it also reports 1200MHz as the current speed (though I can see that it's set to 100x35, also tried 100x36 just to see).

Intel XTU shows that the CPU is thermally throttling (which might be a red herring, as I read that some versions of XTU have a bug that can manifest itself like this). The screenshot below shows what's happening in Windows. I've got Prime95 open and running a blend across all 4 cores and all 4 hyperthreading threads. Task manager shows the CPU at 34% load, XTU shows 100% load, and CPUz shows that it's throttled to 100x12. As you can see on both realtemp and XTU, my temps are fine, and certainly nowhere near throttled.


click for full-size image

Oh, I've also tried flashing the BIOS to the latest (beta) which I know supports the CPU.

Thanks in advance.

[StyM]

what's your bios settings ?

[paradigital]

Hi, thanks for replying.

As far as I remember (not at the machine right now, but will confirm later today), I've reset the BIOS/EFI to factory defaults with the exception of changing the SATA mode (not sSATA) to RAID (for my two FireCuda 2TBs to run in RAID1).

Are there any particular BIOS settings I should be checking for? I assume you are thinking down the lines of Turbo boost settings, or C1E?

I've got the NZXT H440's fan controller plugged into CPU_FAN (as it needs a PWM signal), and I've got the D5's RPM lead connected to CPU_OPT.

[StyM]

mine was turbo on all cores, speed step disabled, c state disabled
high performance on windows power management.
my 2686 is running at full speed even at idle, lol.

[paradigital]

It's OK, I was being an utter numpty. Hadn't realised that I'd knocked the OC_TGR switch (forcing the CPU onto it's lowest multiplier).

My bad