Possible Core Temp Diode bug

[Claviger]

I tried two different BIOS setups last night.

i7 3820, Rampage 4 Gene, BIOS 1305, 125x39 1.504 Vcore loaded, Prime95 with AVX Win7 SP1

Turbo Mode: All Core 125x39
Turbo Mode: Per Core 125x39 (39 set for all entries in the per core section to force 39)

With All core mode temps under load were
Core 0:71
Core 1:67
Core 2:67
Core 3:70

With Per Core mode set and no other changes temps were
Core 0:77
Core 1:77
Core 2:76
Core 3:77

Running the exact same setups for all other settings, exact same software environment, and exact same thermal loading. Testing done within 5 minutes of each other in the same location with same ambient temps.

Clearly there is some witchery going on with this and now I am not sure which setting's temperatures to trust, can anyone else duplicate this?

[Arne Saknussemm]

That is an interesting result. I like the experiment! Maybe by core is more demanding than all core and needs more juice?

When I get back to my PC I'm going to investigate this with my 3930k. I'll post back.....

[Claviger]

I eagerly await your results, if it can be duplicated, then ill do some further testing. If not I'll pretend it didn't happen and move on lol. In Benchmarks I pull the same scores either way, infact, "All Core" scored the best for me by a .016 millisecond time in Wprime at the same speeds.

[Arne Saknussemm]

OK, so I just went into my bios and changed to per core and set 46 for each. This is the only change I made. Normally I have 46 all core. I booted up.... and windows hung on the loading screen. Reset.... booted again BSOD 0x101.....so not enough juice.

My overclock is rock solid stable for everything I have thrown at it! But I know I have shaved power/voltage down to the wire to run it. If per core does not boot for lack of volts it means per core needs more than all core even if the multipliers are the same.

More volts higher temp which is what you were showing.

I suspect your all core voltages could be shaved a bit if your per core boots just at a higher temp.

[Claviger]

Good point, I'll take a look, would account for higher temps, but doesn't account for cores 1 and 2 suddenly being within 1c of 0 and 3 when on all core they are usually 3-6c apart.

[Zka17]

I tried two different BIOS setups last night.

i7 3820, Rampage 4 Gene, BIOS 1305, 125x39 1.504 Vcore loaded, Prime95 with AVX Win7 SP1

Turbo Mode: All Core 125x39
Turbo Mode: Per Core 125x39 (39 set for all entries in the per core section to force 39)

With All core mode temps under load were
Core 0:71
Core 1:67
Core 2:67
Core 3:70

With Per Core mode set and no other changes temps were
Core 0:77
Core 1:77
Core 2:76
Core 3:77

Running the exact same setups for all other settings, exact same software environment, and exact same thermal loading. Testing done within 5 minutes of each other in the same location with same ambient temps.

Clearly there is some witchery going on with this and now I am not sure which setting's temperatures to trust, can anyone else duplicate this?

It's interesting to see that with both setups the core temps are increasing from core#0 to core#4 in a pretty regular manner. Yes, it's known that there is a slight difference between core temps, but I never seen such a regular increase between them. It makes me wondering if the CPU cooler/waterblock is mounted properly... It seems that on one corner is more tightened then on the others... Or, maybe the thermal paste distribution?

[Claviger]

It's been consistently disparate between the 4 cores through i think 6 mounts, with 3 types of TIM and two different water blocks. I can say that baring any odd physical IHS warping, my mount applies even pressure every single time since I use number of threads showing on the mounting studs for my water block to verify even torque. I have tried various pressure points, and while more pressure yields lower temps, there is still a 3-6c disparity.

The disparity of core0/3 vs 1/2doesn't bother me, but the disparity of all core vs per core does :P

[Zka17]

Yeah, but the surface of the CPU is not completely flat... But, yes, this was just a thought - if that doesn't bother you, it's fine!