12V droop when running Furmark?

[skypilot]

I've been running some tests on this new rig, and I notice something disconcerting in SpeedFan: When running Furmark to stress-test my video card, my 12V reported voltage drops from 11.98V to 11.52V. I bought this power supply on the recommendation of a friend, and it exceeds the specs required by the 9800 GTX+ (it has 36A total on 2 12V rails).

Anyone else see a drop like this while stressing the vid card but still have 100% system stability?

System specs:
Biostar Geforce 7100 Motherboard
e5200 @ 2.5Ghz (stock speed)
2x2GB PQI DDR2-800
Geforce 9800 GTX+
Cooler Master Extreme Power Plus 500W PSU (2x18A 12V rails)
1 SATA HDD, 1 IDE DVD

 

[theAnimal]

See here.

 

[cusideabelincoln]

1) As advertised, that unit DOES NOT put out 36A on the +12V rails. If you look at the label, it clearly says it can only put out, with the +12V rails combined, a power of 360W, which is 30A.

2) Your friend is a moron (sorry); it is a crappy power supply and should not have been recommended with a video card such as yours. It should work fine (meaning it should be enough to power the system), but there are many better PSUs out there.

3) There is nothing extreme about those Cooler Master PSUs. Read this review of the 460W unit. I use this as a comparison because the 500W and 460W are made by the same company (ACBEL POLYTECH INC) and I bet they have a very, very similar design layout. In conclusion, the 460W unit was not able to put out its rated 460W and actually performed more like a 350W unit, and I wouldn't doubt if the 500W unit was any different in not being able to actually output 500W.

And to answer your question, yes I have seen a a drop of that difference and have a stable system, although the voltage never got that low. When running OCCTs GPU test, (IIRC) I see my +12v go from ~12.2V to ~11.8V.

 

[Schmide]

ATX specification voltage must be within 5%. You're looking at a 3.8% drop. For what you have in that system, especially if you have a 55nm gtx+, that is quite a drop.

Totaling load

Biostar Geforce 7100 Motherboard = 20w
e5200 @ 2.5Ghz (stock speed) = 30w
2x2GB PQI DDR2-800 = 6w
Geforce 9800 GTX+ = 80w (55nm) 110w (65nm)
1 SATA HDD, = 7w
1 IDE DVD = 2w
Fans =15w

total 80w + (80w - 110w) = 160w - 190w

Yeah that's kind of crappy for running at 32%-38% of total wattage.

Still I wouldn't worry about it. If you get below 11.4v you should start worrying.

 

[MarcVenice]

Software readouts are CRAP.

It's totaly normal for the 12v line to drop a little when you put some load onf it though. Get a multimeter for some real numbers, or just replace the PSU. Don't jump to any conclusions based on speedfan though!