Analysis of overclocked Core i7 TDP figures.
There have been a couple of articles looking at the power requirements of Core i7 processors using various frequencies and VCore settings, but none of them have broken down the results into simple W/Clk and W/VCore factors. That's what I set out to do here in order to give a very general assessment of the Core i7's power requirements, and thus thermal properties.
As the basis for my analysis, I used the power draw results from this article on HardOCP.
This table shows some figures I was able to extrapolate from their results:
The values that I feel are most important are highlighted, and they are the average wattage delta per frequency Mhz (0.0366) and per VCore Volt (329.66) constants.
These values represent ballpark wattage deltas for a given Core i7 frequency and vcore on an ASUS Rampage II Extreme.
Using the values, we can assert the following function for overclocked TDP:
OC_TDP = BASE_TDP + (ASUS_EFFICIENCY * ((FREQ_DELTA * 0.0366) + (VCORE_DELTA * 329.66)))
So... Next order of business: How efficient is the PWM circuit of an ASUS Rampage II Extreme running at 100% load? Once that bit is plugged in, we should have ourselves a reasonably accurate Core i7 TDP calculator for any platform.
One additional note:
Technically, processors become less efficient the higher their internal frequency. The wattage/Mhz deltas in the spreadsheet illustrate this, and any final model should take into account the compounding loss in efficiency as frequency increases. The spreadsheet does do this currently for projecting the (d)W/(d)Mhz factor for the 1.35V-3.8Ghz data item.
If you are curious as to particulars, you can download the spreadsheets (attached). I commented a lot of the cells to explain my methodology.
Let me know if you guys spot any errors, or if anybody knows the Rampage II PWM efficiency figure.
As the basis for my analysis, I used the power draw results from this article on HardOCP.
This table shows some figures I was able to extrapolate from their results:
The values that I feel are most important are highlighted, and they are the average wattage delta per frequency Mhz (0.0366) and per VCore Volt (329.66) constants.
These values represent ballpark wattage deltas for a given Core i7 frequency and vcore on an ASUS Rampage II Extreme.
Using the values, we can assert the following function for overclocked TDP:
OC_TDP = BASE_TDP + (ASUS_EFFICIENCY * ((FREQ_DELTA * 0.0366) + (VCORE_DELTA * 329.66)))
So... Next order of business: How efficient is the PWM circuit of an ASUS Rampage II Extreme running at 100% load? Once that bit is plugged in, we should have ourselves a reasonably accurate Core i7 TDP calculator for any platform.
One additional note:
Technically, processors become less efficient the higher their internal frequency. The wattage/Mhz deltas in the spreadsheet illustrate this, and any final model should take into account the compounding loss in efficiency as frequency increases. The spreadsheet does do this currently for projecting the (d)W/(d)Mhz factor for the 1.35V-3.8Ghz data item.
If you are curious as to particulars, you can download the spreadsheets (attached). I commented a lot of the cells to explain my methodology.
Let me know if you guys spot any errors, or if anybody knows the Rampage II PWM efficiency figure.
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Comments
Without knowing the ACTUAL base TDP of a Core i7, since Intel is sticking us with this horse shit 130W TDP rating, it is almost impossible to determine the PWM efficiency of a given motherboard at load. You have to have SOME jumping off point. It may be that it is impossible to complete my formula with current data.
Hrmpf. Ain't that just a kick in the balls? Since the socket changed, we can't even use some older processor with a known TDP to determine the motherboard's PWM efficiency.
Anybody know of existing tests on the Rampage II to determine PWM efficiency, or does anybody have information on the REAL TDP of a Core i7 920? Which is what the HardOCP tests were performed with.