Barcelona Opteron 2350(B1) arrived

[Mad_Man]

i though that power draw scales ^2 with voltage. Or i was told so a while ago on this forums...
so if its 68W @ 1.1V it should be (1.25/1.1)^2*68= ~88W or 20W more at 1.25V

[Cronos]

note. these calculations are by no means accurate. i have assumed the current a CPU draws is constant, etc. But at least it provides an indication
At stock, the procecessor's TDP is 68W. Stock is 1.1V, so 68/1.1=6.18A. Now if you feed it and extra 0.15V, that mean 6.18*0.15=0.93 extra watts, a lot of which isnt actually being used (TDP is a theoretical maximum), and therefore the difference is not large enough to show up when measuring power, especially not of the whole system.

Current draw is not constant, it depends linearly on voltage.
Power draw scales as Clock* Voltage*Voltage.
In this case, increasing voltage from 1.1v to 1.25v gives (1.25/1.1)^2 = 29% increase in power draw. So, CPU with 68W TDP becomes 89W.

[Mad_Man]

when you factor in C/W values... if you are ~30C above ambient at stock, raising the Vcore from 1.1 to 1.25 should add very roughly 8.8C to your load.

again, these are very rough equations, but i found they are pretty close to real world data. even if your cpu uses less wats than its TDP (and it actually does use less) its correct to certain margin of error, because than difference between actual power draw and TDP is on both sides on equation.

I experimented with them on my system to "guess" core temp at certain speed/volts and then i found they are +/- 1C from real values.

if something is unclear in my post, dont shoot me... i tried my best with my english lol


edit: Cronos, you were 3min late lol

[indiana_74]

Current draw is not constant, it depends linearly on voltage.
Power draw scales as Clock* Voltage*Voltage.
In this case, increasing voltage from 1.1v to 1.25v gives (1.25/1.1)^2 = 29% increase in power draw. So, CPU with 68W TDP becomes 89W.

Okay, so I understand you right when I say that there must be a difference when I rise the Vcore from 1.1V to 1.2V.

Note that the CPU are working at there limit when I messure the wattage.

All eight cores are at fully load with QMC workunits and on my other systems i can see a difference when I change it only for 0.05V.

[Mad_Man]

Okay, so I understand you right when I say that there must be a difference when I rise the Vcore from 1.1V to 1.2V.

Note that the CPU are working at there limit when I messure the wattage.

All eight cores are at fully load with QMC workunits and on my other systems i can see a difference when I change it only for 0.05V.

then maybe you're not changing the vcore properly... can you measure the Vcore from VRM mosfets with DMM? that would tell you