shinji2k's Power Consumption Tests - Overclock.net

shinji2k · 07-11-09

See Post #7 for most accurate video card power consumption results!

This is just a little teaser since I don't have everything I need, but I eventually plan on measuring actual power consumption of some components I can get my hands on. I need to get some cable extenders and a ribbon type PCIe slot extender to measure the power consumption of video cards. I can separate the power wires from the ribbon to measure what the PCIe slot itself is supplying. For now though, you just get to see my Kuma 7750 in action. If anyone cares, the PSU being used is a BFG LS-450 and the clamping ammeter is a Mastech MS2138R (not exactly the best, but it's all I can afford).

Loaded her up and took some measurements.

Idle is at 1.9A and 12.18V measured at the 8-pin EPS12V connector. Load as you see in the pic, was at 6.8A and 12.08V at the connector.

So for a very slightly OCed Kuma (the mobo sucks), I've got 23W idle and 82W load.

I did some more measurements at different clock speeds at stock voltage (stupid mobo).

I know it is only a couple data points, but power consumption is fairly linear with changes in frequency so long as voltage stays the same. In the future when I use a better mobo I can play with voltages too to see how that affects everything.

When I get around to buying the rest of what I need I can test a skt939 4400 x2 and a Q6600. I've also got my old 7800gt, a gts250 and my two hd4780s I can look at. But that will have to wait for another day.

I also realize this isn't the most accurate. Measuring static loads are fine, like Prime95 or Furmark, but when I try to do in game power consumption it will not be very accurate. Loads can change very quickly, these are called transients. A simple meter like I have will completely miss those. I could make some inline shunt resistors and get a cheapo digital scope to measure and record voltages, but even that would run me at least $250. But I hope it will be interesting enough.

Enigma8750 · 07-11-09

Actually I am looking forward to your future thread on this matter. It is very important to take into concideration the amount of power the board with the CPU clocked up is eating. I wish you had an old Quad lying around that you could drop into that and get a reading. Like a 940 or a 9850. Great work. Rep up.

M1 Abrams · 07-11-09

Good job, keep it going

shinji2k · 07-11-09

I need to make/buy some power connector extensions to make it a little easier to use the ammeter and something like an 8" PCIe slot extender before I can do much else. I happened to have just enough exposed wired on this PSU to squeeze the clamp in there on the 8-pin CPU. I also plan on expanding my load tests to 3dmark06, Vantage, Prime95, Furmark, Crysis, Stalker:CS and whatever I else I have on my gaming rig at the time. And if I can get a folding client I'll even take a look at the gts250.

shinji2k · 07-15-09

Got some of my connectors in today and I've done some more measurements. First off I looked at my Q6600. This should be self explanatory.

Stock load was pretty low at 67W, and with this chip at it's max (it's a crap one) it's upwards of 150W. This is measured at the 8-pin EPS12V connector so this is just the CPU.

Next, I tested one of my 4870s. I don't have my PCIe slot extension in yet, but since I have two 4870s I can do some estimating to get what the card draws through the slot. To do that I loaded up both cards and measured power consumption at the 24-pin. Then I removed one card and repeated. Subtract out the difference and you get what one card draws and what the mobo itself draws on the 12V rail. It turns out the mobo draws an average of 6W for itself. So when I test other video cards I just have to measure at the 24-pin and subtract out 6W to get a close estimate.

That's a little confusing but you should get the drift. The 4870 drew 79W at idle, 128W during 3dMark06, 142W during Vantage and 213W using a renamed Furmark. ATI limits Furmark since it has the possibility of frying the VRMs. If I hadn't changed the filename, it would have only drawn 135W.

This was just a quick test, but it still took a while. When I get some time I will try to get some readings on what the mobo itself draws on the 3.3V, 5V and 12V rails as well as DDR, DDR2 and DDR3 RAM power consumption. I've still got my skt939 board to look at and a couple more video cards. I will also try to get some readings for a few of the more popular FPS games.

shinji2k · 07-15-09

I've had a look around to compare my results. Xbitlabs uses 3dMark06 to test power consumption. My results for 3dMark06 are pretty close to theirs, although my idle is high. That may be due to my estimating so I will have to recheck when I get my extension in. These guys tested with Furmark. I'm also a little higher than their results, but my video card is clocked a little faster at stock so that may be where some of the difference is. I really should try power consumption at reference clocks as well for the 4870 (750/900). So far it looks like I am in the ballpark.

shinji2k · 07-18-09

Through some testing I discovered my motherboard draws a constant 0.5A through the 24-pin connector. Knowing this made it pretty easy to calculate power draw through the PCIe slot. So I've retested my 4870 and I've also added a few more cards and added a couple game benchmarks.

I started testing my 4870 at reference clock speeds but I didn't notice much difference from the Furmark results. Because of that I didn't feel the need to waste the time testing the rest. These are all the video cards I have and I can't really buy cards just for testing so this is all the video cards I'll be able to test for now.

If anyone is interested I can do some detailed testing on these motherboard/CPU combos:
DFI LP SLI-DR/skt939 4400 X2
Jetway PA78VM5/Kuma 7750
ASUS Max Extreme/Q6600

But I doesn't seem like many people care. These tests take forever and I'd prefer not to waste my time.

daffy.duck · 07-18-09

Quote:

Originally Posted by shinji2k

But I doesn't seem like many people care. These tests take forever and I'd prefer not to waste my time.

Very interesting read.
I for one appreciate your hard work.
Keep it up.

shinji2k · 07-18-09

Quote:

Originally Posted by daffy.duck

Very interesting read.
I for one appreciate your hard work.
Keep it up.

Thanks. It's a pain in the butt doing the video card tests. I only have one meter and four things to measure (amperage and voltage of the 24-pin and the one/two PCIe connectors) so I usually end up running each benchmark at least twice.

DuckieHo · 07-18-09

Interesting results on the GTS250.... it is drawing over 100w on the PCIe connector? Does that violate ATX PSU specs?

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shinji2k's Power Consumption Tests

07-11-09	#3 (permalink)
M1 Abrams Overclocker Join Date: Apr 2009 Posts: 635 Rep: 59 Unique Rep: 51 Trader Rating: 0	Good job, keep it going

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