I don't know how much use what I am about to say is, but I have given up trying to get my 8120 to hold steady clock speeds or use TurboCore properly. I'm certain it lies with MSI's BIOS doing something a little weird, but I can't be sure and don't have the time to do some detiled troubleshooting.
I try to run my FX at an OC of 4.8 Ghz (200 * 24), with CnQ turned on and Turbo Core. When I run this set-up, from time to time when I say stress the CPU's 8 threads (I had choose 8 ) in Prime95, it either:
- Does not clock up the CPU from idle state. It stays at 1400Mhz per core as per idle conditions or will fluctuate between idle and OC (or stock speeds as in your case). Or...
- Clocks up to it's rated Turbo Core speed (4 Ghz), but only 4 threads show activity (I chose 8 ).
If I run the OC as before, but turn off Turbo Core at BIOS level, the 2nd problem above never happens. All 8 "cores" ramp up to 4.8 Ghz in that scenario. Sometimes idle state is still invoked for whatever reason with Turbo Core turned off, and it's seemingly at random. Only way I stopped that happening was to turn off CnQ, but then it leaves the FX at 4.8 Ghz all the time (Eeeeek, the power consumption). Stock speeds don't make any difference neither, one or both of the above still happens.
It doesn't get hot enough to be clocking back. Under max CPU load with the CF Radeon's going into meltdown heat wise, the CPU hovers at about 50-60C on the 4.8 Ghz OC. Idles in the high 20's to low 30's otherwise.
IMO, Turbo Core seems broken, as it shouldnt ramp up to 4 Ghz anyway when it's got 4 thread workload acording to AMD, and it looks like Core Parking or thread scheduling isn't working properly. It's the only reason I can think of causing the issue of an 8 thread workload only being split across the FIRST 4 threads in Task Manager. Half the CPU appears to be asleep, and performance suffers. Scheduling the workload properly over every other "core" first makes a small improvement according to the benchmarks, but W7 doesnt do this but apparently W8 does with a dozer CPU...
Either way, mine does the same strange behaviour as yours, and welcome to TR.
The Piledriver Beast - AMD FX-8350 (4.4 Ghz) | Gigabyte 990FXA-UD5 | 16GB Elite Group DDR3 1600 | Crossfire XFX "DD" R9 290X | Crucial 512GB M550 SSD