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How close to 5v and 12v is the PSU supposed to get?

A

AgentZap

Senior member
I have a Seasonic 500 watt PSU with dedicated 6 pin SLI connectors

When I get into Windows the nvidia drivers report that my BFG 6800 GT is not getting enough power so it is being downclocked.

I have only the one video card and the 6 pin line is hooked into it. Its a PCI Express card.

I don't have too much else hooked in:
AMD 64 4000+
MSI K8n Neo4 Platinum SLI
1 Hard Drive
1 CDROM

I ran a program called everest and it reported 4.87 on my 5v line and 11.73 on my 12v line. Are those numbers low? How close are they supposed to be?
 
Those numbers seem fine to me, I think you want them to be within 5% or so of spec. I don't know why it would be reporting that the video card isn't getting enough power....😕

Edit: For reference, my 5V and 12V numbers are 4.87V and 11.86V, respectively. I have the Seasonic 600W power supply.
 
Originally posted by: SynthDude2001
Those numbers seem fine to me, I think you want them to be within 5% or so of spec. I don't know why it would be reporting that the video card isn't getting enough power....😕

Edit: For reference, my 5V and 12V numbers are 4.87V and 11.86V, respectively. I have the Seasonic 600W power supply.
Click to expand...

You will want to use a multimeter to test voltages if you haven't already. Onboard voltages can be wrong by more than .30 sometimes.
 
Hmmm...what clues does this provide I wonder...

The video card comes with a Y adapter that takes 2, 4 pin molex connections and outputs to one 6 pin connector for the video power.

If I use that to power the card instead my computer does not even turn on.
 
Originally posted by: dguy6789
Originally posted by: SynthDude2001
Those numbers seem fine to me, I think you want them to be within 5% or so of spec. I don't know why it would be reporting that the video card isn't getting enough power....😕

Edit: For reference, my 5V and 12V numbers are 4.87V and 11.86V, respectively. I have the Seasonic 600W power supply.
Click to expand...

You will want to use a multimeter to test voltages if you haven't already. Onboard voltages can be wrong by more than .30 sometimes.
Click to expand...


I am a total electrical n00b, where do I put the multimeter diodes on the connectors to test that?
 
As measured with a Fluke 87 meter under Prime95 max heat load:

Enermax 495 Noisetaker V2.0 power supply with AX8 board and AMD 64 3000 Winnie
12VDC...measured 12.06VDC
5VDC...measured 5.12VDC

Most quality power supplies will remain stable within plus/minus 0.15VDC

It is safe to measure the 12V and 5V rail at the molex connector. Black to black, and red on multimeter to Red or Yellow of molex. These wires are connected in parallel to the circuit board, so you will see an accurate reading at the output stage.

A very good powersupply should control the voltage to within 0.2VDC of the target value.
 
You can connect only the hard drive and video card to the power supply and retest with Prime95 and a calibrated multimeter. It is rare for a quality power supply to go below 11.8VDC with this test.
 
I picked up another power supply rated at 480w (antec) and it was reporting much closer to spec than the seasonic, but I still had the same issue.

I wonder what I should do now.
 
here's my software monitoring is useless pic. note the 12v reads 11.71 in windows but 11.99 on a dmm.

as a side note, is there any more load i can add, i have encoding, prime, rthdribl going.
 
I'm getting the following in my 3.6 P4 rig.. this is using an Antec 550EPS psu

+12v = 12.038
+5V = 4.999
+3V = 3.312

For a new psu you should get tighter reading.

Maybe it's the dual rail design that's affecting your rails ??
 
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