the easiest way to meassure is to put your gpu on a usb riser and measure all the 12v lanes (and the 5volt lane) with a clamp meter !!!

and dont forget to add your average 10% due to psu loss (there is no 100% power conversion and leaving that out is PLAIN FALSE)

Still something strange is going on here… the values are totally OFF by about a HALF.

I use a DC clamp meter to measure my gpus.

As I said above the most accurate way to do it is to use a powered usb riser cuz you can easily meassure all the power going to the gpu: (as you did)

In my case eg for Jackpot:

Gigabyte 750ti
core clock 1250 mhz
mem clock: stock

hashrate ~ 5100 khash/s

through the pci-e plug (yes this 750ti has one) flows: 1.6 amp @ 12v
through the molex plug to the pci-e slot flows: 2.2 amp @ 12v
and YES through the 5 volt molex plug flows: 0.250 amp @ 5v (which is converted to 3.3 volt onboard the pci-e usb extender)

1.6 times 12 = 19.2 Watt
2.2 times 12 = 26.4 Watt
0.250 times 5 = 1.25 Watt

Total wattage = 46.85 Watt
times 1.1 = 51.54 Watt (standard Gold power supply)

My 750ti is not recognized correctly under device manager if I remove the 6 pin pci-e plug.

Besides that the Palit 750ti is meassured to draw 7.65 watt idle. The lowest ever meassured 750ti was 6+ Watts in idle and up to 8 Watts. (everything stock)

And tada your meassured 3.8 Watt is exactly HALF again of what it should have (7.65).

(The above has been meassured not by me but by several online hardware testers.)

Once again your meassurement is half off this tells me your meassurement device is used in a wrong way …

We have tried with two different power meters and the results we are getting pretty much the same on both, the accuracy on these might not be 100%, but the tolerance should not be more than 1-3%.

But let us look at this in another way, let us say the GPU is using 8W at idle with the whole system idle at 38W, so the system uses 30W of power when idle. If the GPU uses 50W at load while mining and the whole system is at 80W under load, there are again 30W for the rest of the hardware (not 100% load, but higher than when idle), so this cannot be right. We have a motherboard, a 54W MAX TDP CPU, memory, CPU cooler plus two additional fans, hard drive…

The power supply is more like 70% according to the manufacturer specs: http://www.coolermaster.com/powersupply/extreme/extreme-power-plus-500w/

“Our Extreme power supplies provides over 70% efficiency at typical loading” and at 100W out of the 500W rating of the PSU I doubt it can deliver more than 70% efficiency as the typical rating they talk about is probably more like with 50% load of the PSU.

What is wrong in your calculations is that you still use the idle power of the system as the power consumption when it is under load, at idle the CPU lowers the operating frequency and voltage, so the power consumption is lower as well, the same goes for the other components as well, though there the difference is smaller. While mining it is not in power saving state anymore and it does consume more power, not at 100% load of course, but mining does need some CPU power as well (varying between algorithms). So the power used by the system under load excluding the video card is at least 40W or maybe even more, with light system usage (GPU in 2D mode, not mining) the measured power at the wall is around 50-55W on the power meter (this includes the GPU usage)…

Anyway, the idea of this post was not to focus on the GTX 750 Ti power usage only, but to see the power usage of different algorithms supported by ccMiner. Different algorithms do have varying impact on the whole system usage, most notably the CPU of course, so the total power usage of the system is actually more important when considering the mining costs as you pay for the electricity used by the computer measured on the wall.

Why don’t you make these same measurments one more time, but this time with 2 videocards?
Case solved :)

PS: add cryptonight (monero/quazar/bytecoin)

Where are the Scrypt, Scrypt-N, Protoshares, Primecoin and Monero results? :D

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