Hi,
I want to understand power limit a little more for AMD Radeon HD cards. I understand it increases the power the card can consume if required. I run with power limit +20% in Sapphire Trixx and and a standard clock for the Sapphire Radeon HD 7950 Vapor-X 950MHz. Trixx also VDDC has 1006 I believe it should be read 1.006.
The stats from GPU_Z logging I am getting in Elite Dangerous: -
Date GPU[MHz] GPUMem[MHz] GPUTmp FanSpd(%) FanSpd(RPM) GPULoad[%] MemUseDed[MB] MemUseDyn[MB] 12V[V] VDDC[V] MVDDC[V] VDDC[A] VDDCIn[A] VRM1Tmp VRM2Tmp
23/08/2014 23:51 950 1250 63 83 3315 93 0 1158 11.59 1.021 1.5 113.8 14 60 54
23/08/2014 23:51 950 1250 63 83 3333 92 0 1158 11.56 1.012 1.5 135.5 13.6 60 54
23/08/2014 23:51 950 1250 63 83 3340 91 0 1158 11.56 1.025 1.5 101.8 11.8 60 54
23/08/2014 23:51 950 1250 63 83 3320 91 0 1158 11.63 1.023 1.5 119 14.6 60 54
23/08/2014 23:51 950 1250 64 83 3314 91 0 1158 11.59 1.016 1.5 139.5 15.1 60 54
23/08/2014 23:51 950 1250 64 83 3318 92 0 1158 11.66 1.029 1.5 110 13.7 60 54
23/08/2014 23:51 950 1250 63 85 3328 92 0 1158 11.53 1.01 1.5 121.3 12.3 60 54
Now from high=school phsyics: -
power = voltage x current
voltage = current x resistance
hence power = current squared x resistance
therefore as you increase power current, voltage and resistance must be increasing. I'm guessing that in the background +20% power limit is icreasing these (voltage and current). So now I want push on from 950MHz. Temps look good but what about the voltages and currents being used currently are they within the capabilities of what the card can handle?
The plan of action: -
Step1
See what happens as I increase GPU speed to find a max stable overclock whilst keeping the power limit at +20%. See here means to evaluate temps, voltages and current to remain within sensible range. I don't want to be at the bleeding-edge as that can be painful.
Step2
If all is well then how far can I push the power limit sensibly whilst keeping temps, voltages and currents within sensible limits and what are those limits? Does power limit actually work-out what are safe temp, current and voltages? How does it work this out does it have some sort of lookup table?
My question is also what are sensible temps, current and voltages? Sensible is also open interpretation. Your thoughts, comments and musings most welcome.
Thanks
Haider
EDIT
Apologies cut and paste of table has not kept the spacing...
I want to understand power limit a little more for AMD Radeon HD cards. I understand it increases the power the card can consume if required. I run with power limit +20% in Sapphire Trixx and and a standard clock for the Sapphire Radeon HD 7950 Vapor-X 950MHz. Trixx also VDDC has 1006 I believe it should be read 1.006.
The stats from GPU_Z logging I am getting in Elite Dangerous: -
Date GPU[MHz] GPUMem[MHz] GPUTmp FanSpd(%) FanSpd(RPM) GPULoad[%] MemUseDed[MB] MemUseDyn[MB] 12V[V] VDDC[V] MVDDC[V] VDDC[A] VDDCIn[A] VRM1Tmp VRM2Tmp
23/08/2014 23:51 950 1250 63 83 3315 93 0 1158 11.59 1.021 1.5 113.8 14 60 54
23/08/2014 23:51 950 1250 63 83 3333 92 0 1158 11.56 1.012 1.5 135.5 13.6 60 54
23/08/2014 23:51 950 1250 63 83 3340 91 0 1158 11.56 1.025 1.5 101.8 11.8 60 54
23/08/2014 23:51 950 1250 63 83 3320 91 0 1158 11.63 1.023 1.5 119 14.6 60 54
23/08/2014 23:51 950 1250 64 83 3314 91 0 1158 11.59 1.016 1.5 139.5 15.1 60 54
23/08/2014 23:51 950 1250 64 83 3318 92 0 1158 11.66 1.029 1.5 110 13.7 60 54
23/08/2014 23:51 950 1250 63 85 3328 92 0 1158 11.53 1.01 1.5 121.3 12.3 60 54
Now from high=school phsyics: -
power = voltage x current
voltage = current x resistance
hence power = current squared x resistance
therefore as you increase power current, voltage and resistance must be increasing. I'm guessing that in the background +20% power limit is icreasing these (voltage and current). So now I want push on from 950MHz. Temps look good but what about the voltages and currents being used currently are they within the capabilities of what the card can handle?
The plan of action: -
Step1
See what happens as I increase GPU speed to find a max stable overclock whilst keeping the power limit at +20%. See here means to evaluate temps, voltages and current to remain within sensible range. I don't want to be at the bleeding-edge as that can be painful.
Step2
If all is well then how far can I push the power limit sensibly whilst keeping temps, voltages and currents within sensible limits and what are those limits? Does power limit actually work-out what are safe temp, current and voltages? How does it work this out does it have some sort of lookup table?
My question is also what are sensible temps, current and voltages? Sensible is also open interpretation. Your thoughts, comments and musings most welcome.
Thanks
Haider
EDIT
Apologies cut and paste of table has not kept the spacing...
