Intel 6700K with HT enabled has performance loss in low threads(1 to 4) stress

[kwong_]

I performed many stress tests using LinX, the results fluctuated in 3 or 4 threads' stress tests.
Compare to the same settings without HT, the 3 threads' stress has approx. 15% loss in performance.

My 6700K had no such problem last year, but there are great performance loss in low threads(1 to 3) stress after BIOS update this year. Is this the side effect of Skylake Bug Fixing?

8 threads' stress is no problem and stable, but I concern low threads' performance too.

Disabling HT can solve the problem, but I don't want to treat my CPU as 6600K... I hope there are some other workarounds for the performance loss and I do want to know if the problem is on MSI MB only.

Here's my settings:
Hyperthreading:Enabled
CPU:44x
RING:40x
RAM:16GB-2133MHz-15-15-15(CPU was stable even with higher memory freq. last year)
SA/IO:1.05/0.95(many combination had been tried)
VCORE:1.350v
MB:MSI Z170A-G45

 

[wingman99]

The performance loss is just the HT on the CPU, unless you can prove it by going back to the bios that gave you more performance.

 

[kwong_]

Thanks for the reply. I've downgraded the BIOS and the result is... Disappointed! It's as same as that of the new BIOS.
Maybe there were not much background applications running last year as the Windows was freshly installed.
Okay, I just state the results of 3 threads' stress for reference here:-
LinX test with 8192MB
Comparison 1:
w/o HT ~188GFlops
w/ HT 155 to 167 GFlops
Comparison 2:
Jul 2016 w/ HT: 155 to 167 GFlops
Fresh Windows on Nov 2015 w/ HT: ~182GFlops
Fresh Windows on Nov 2015 w/o HT: ~186GFlops

 

[wingman99]

HT does add some overhead it always has, there is only 4 cores and HT threads some of the same programs with 2 threads to 1 core that can cause a traffic jam while threading. HT helps out when you have a lot of multitasking programs. I don't do those sort of things that is why I don't have a HT CPU.

 

[ATMINSIDE]

It takes cycles from the cores to run the extra threads