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Low voltages

C

charlok

n00b
Joined
Feb 24, 2006
Messages
20
Ok, this is really driving me insane.

I discovered low voltages on my Antec TruePower 2.0 550W about 2-3 weeks ago (4.49V across the 5V rail, ~11.3V across the 12V rail, <3V across 3.3). I saw these voltages in two software sources, and although I know these are frequently inaccurate, +10% deficits reported by 2 sources makes me wonder. I RMA'd the power supply and received a new one (same model) this week. Well, I'm getting the same low voltages with my new power supply, and I verified it with a multimeter.

I don't know much about what can cause low voltages, but I think this power supply should be able to handle my PC's load. What can cause this problem? Could I have gotten two bad PSU's, or am I somehow setting the connections wrong? I've been building computers for several years, so I'm pretty sure I've set it up correctly.

Specs:
Asus A8N SLI Premium
AMD X2 4400+
BFG Tech Geforce 7800 GTX OC
WD Raptor 74GB
2GB Corsair XMS PC3200
And (of course) Antec Truepower 2.0 550W
 
What exactly were your voltages with the DMM on the new supply and how did you take them?
 
I took them using the 24 pin connector.

2.85V across 3.3V, using orange and black wires
4.45V across 5V, using red and black wires
11.29 across 12v, using yellow and black wires

I should add that these are the values immediately after the PC is turned on.
 
charlok said:
I took them using the 24 pin connector.

2.85V across 3.3V, using orange and black wires
4.45V across 5V, using red and black wires
11.29 across 12v, using yellow and black wires

I should add that these are the values immediately after the PC is turned on.
Click to expand...

What happens under load?
 
Not sure. I decided since I had to wait for my PSU to come back from Newegg, I would buy a new hard drive too :D. So I don't have anything loaded on the PC yet; the first thing I decided to do was check my voltages with the new power supply. Should I load my O/S and test it under load? I can say that when I had the first power supply, I ran the PC for about a month. I would notice (in games like Halflife 2) chippiness and FPS spikes, which originally led me to check the voltages in the first place. I'm just really perplexed :confused:
 
charlok said:
Not sure. I decided since I had to wait for my PSU to come back from Newegg, I would buy a new hard drive too :D. So I don't have anything loaded on the PC yet; the first thing I decided to do was check my voltages with the new power supply. Should I load my O/S and test it under load? I can say that when I had the first power supply, I ran the PC for about a month. I would notice (in games like Halflife 2) chippiness and FPS spikes, which originally led me to check the voltages in the first place. I'm just really perplexed :confused:
Click to expand...


Yeah I would be curious to see what happens under load. Also try the 12v and 5v's at an empty molex as well and the 12v at the P4/AUX. Just a question what type of probes ae you using to get to the back of the ATX connector?

The chances of 2 bad units in a row is remote.
 
Ok I ran 3DMark on my computer and watched the voltage levels.

Throughout the benchmark, the levels stayed pretty much the same as they are at startup:

2.84v across 3.3v
4.44v across 5v
11.25-11.28v across 12v

Now, this is probably a stupid question, but does the amount of voltage coming out of the wall socket affect the voltage? I mean, if the voltage for my house is within spec, it should be way more than enough to power a PSU. The reason I ask is because we know that the voltage coming to our house (and others on our grid) is a little low, but still within spec (so they say). Can this affect my voltages?
 
Ok, perhaps if I rephrase the question someone can give me an answer:
1) Can this power supply http://www.newegg.com/Product/Product.asp?Item=N82E16817103933
handle this system:
Asus A8N SLI Premium
AMD X2 4400+
BFG Tech Geforce 7800 GTX OC
WD Raptor 74GB
2GB Corsair XMS PC3200
Plextor DVD burner
Generic DVD ROM drive
Soundblaster Audigy2 ZS
Linksys WMP54G

2) Are there any possible causes, other than an inadequate PSU, for low voltages? (ie setting the connectors wrong, that sort of thing)
 
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