Why is my i7-9700K so slow and report 207 cores??

[qqdc]

Been using this i7-9700K Octane V for a couple of months. I noticed within the first week it was taking 20 minutes to run something that used to take less than 10 minutes on the i7-7700K machine (Octane III I think). But it has taken this long to sit down and run the Geekbench benchmark on them, side-by-side.
(Both machines are running Linux Mint, have 16GB, the same GTX1070; otherwise the Octane V is higher spec, so should be slightly quicker in all areas...)

The 7700K gets single-core score of 5593, multi-core of 17,885.

But the 9700K says Single: 3748, Multi-Core: 7695.

(Should be about 5900 and 27,000, judging by other machines on geekbench.)

The other strange thing is the CPU info says 207 cores (see full info below).

/proc/cpuinfo reported the same thing (though it did only show info for processors 0 to 7).

Ah, the 8 processors each report a different number for cpu cores:
8, 1401, 1202, 1003, 804, 605, 406, 207

The 7700K also reports 8 processors, and each of them report the exact same "4" for cores. (I.e. the 7700K has 4 cores, and hyperthreading)

Google is turning up nothing. Anyone any idea what is going on??


Name Intel Core i7-9700K
Topology 1 Processor, 207 Cores
Identifier GenuineIntel Family 6 Model 158 Stepping 12
Base Frequency 4.90 GHz
L1 Instruction Cache 32.0 KB x 4
L1 Data Cache 32.0 KB x 4
L2 Cache 256 KB x 4
L3 Cache 12.0 MB x 1

 

[Scott]

My guess is going to be Linux here. I don't know for certain though.

Is there any way for you to install a trial of Win10 and run similar benchmarking to rule out the OS/Chipset Drivers?

 

[ubuysa]

My guess is going to be Linux here. I don't know for certain though.

Is there any way for you to install a trial of Win10 and run similar benchmarking to rule out the OS/Chipset Drivers?

I agree that this sounds like Linux rather than hardware. It might be that Linux has an issue with hyperthreading? Try going into the BIOS setup and turn hyperthreading off, Linux should then report only 4 processors of course.

 

[qqdc]

> It might be that Linux has an issue with hyperthreading? Try going into the BIOS setup and turn hyperthreading off, Linux should then report only 4 processors of course.

It would be the other way round. The 9700K has 8 actual cores, no hyperthreading. So it should be reporting 8 cores.

No easy way to try win10. (except under virtualbox, which would be pointless, I suppose!) I'll try looking for some kernel or driver updates first.

 

[Scott]

As I understand it a virtual machine would work fine, only RAM constraints would be your issue?

 

[qqdc]

I did a kernel upgrade. That (or one of the other updates I did at the same time) fixed the mis-reported cores (now "8" consistently), but performance problem is unchanged.
I also moved from 4.15 to 4.18 kernel, but again the performance is unchanged (there is some noisy variation run to run, but +/-100, nothing that would explain being -2000 and -19,000 from expected values).

I'm wondering why the benchmark reports "Base Frequency 4.90 GHz", when it is a 3.6Ghz chip. I'm not overclocking, but maybe I should check the bios for weird settings.
`watch 'cat /proc/cpuinfo | grep MHz'` is interesting, as I can see each core has its own speed, and sometimes they are all 800, but typically they are all jumping around randomly between 800 and 1500. I've seen one core hit 2000, once.
...and I just kept that going, while running the benchmark again. For the single core tests I'd sometimes see one of the cores register a number above 2000. But for the multi-core they all spent most of their time under 1000.

I.e. even though I'm on mains, not even on battery, and even though all temperatures are still in the 40s, it seems to be stuck in some kind of power-saving mode.

(I'll try and remember to report back if I do discover why.)

 

[Scott]

That definitely sounds like some sort of clock limitation. Base is 3.6 with single thread peak of 4.9. I think all cores should be able to run 4.6ghz though.