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Power source only gives 3V

Posted on 2004-11-27
Medium Priority
Last Modified: 2010-04-25
Hi, first of all I want to apologize for my English.
I have bought a computer about three months ago and it has given me one headache after another.
motherboard: Asus A7V8X-X
processor: Athlon XP 2400+
512 Mb RAM
video card Nvidia FX-5500

It has a 400 W power source. I ran Asus PC Probe and noticed that it was not giving 3.3 V but only about 3.0. And it was giving 12.5, not 12.
Today the computer would not boot up, so I called a technician and he saw that there was a problem with the 3.3 cable. He lent me another power source and it is working, but PC Probe is still showing 3.0 V
a. Is this a problem?
b. Can it be a motherboard problem? Could the motherboard cause the source to fail?
Question by:clau

Accepted Solution

stockhes earned 1000 total points
ID: 12688159
On my nforce2 board (EPOX) all monitors reports the 3,3 volt as 2.7 volts I did a lot of digging into this and found out that it was my Vdimm(ram) that was reported as 3,3 volts.

If you have access to a voltmeter simply measure the voltage between and orange wire(on top of my head) and a black wire

ATX spec says all tolerances is +/- 5% except 12volt where +/-10%

So 12.5 is ok but 3.0 is not

HAve you tried inspecting those values in the BIOS ?

And yes theoretically a motherboard in case of shorting or malfunctioning can "cause the source to fail"

LVL 31

Expert Comment

ID: 12690174
If it runs OK, it may be unimportant. A too low voltage doesn't sound dangerous to me. Besides, these on-board voltage probes, anyone knows how accurate they are? If you are concerned about this, make sure you check the reading with a proper meter.

Author Comment

ID: 12692705
Some more info:
Today I tried the new power supply in another computer and it gives the 3.3V OK.
I am reading the info from the hardware monitor in the BIOS setup.
The new computer does have problems: it freezes, I had to use a USB keyboard because PS2 ones stop responding, I had to install Windows 98 because I had trouble with the video card drivers in Win XP, etc.
Tomorrow I will try another one

Author Comment

ID: 12716424
Well, I did many tests and:
a) tried 2 DIMMs 256 Mb each DDR333 instead of my DDR400 PC3200 512 Mb DIMM - same result
b) tried a GeForce 440 64Mb RAM and the power supply gave 3.1V
c) tried a 450 W power supply and it gave 3.3V

So, my conclusion is that there is something in the motherboard that is eating too much power.

Maybe it is a faulty mobo? Or is it a feature?
Is there a way to verify this?
Stockhes, how can I find out if I have the same RAM problem than you?
LVL 88

Expert Comment

ID: 14596318

No comment has been added to this question in more than 21 days, so it is now classified as abandoned..
I will leave the following recommendation for this question in the Cleanup topic area:
Accept: stockhes

Any objections should be posted here in the next 4 days. After that time, the question will be closed.

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