Psu problems?

[tom]

hello. I just purchased a matx psu to power a basic asus motherboard
two fans, cpu fan, dvd drive/cd and floppy drive. It's a 320 watt
diablotek, and I think it should be enough.(?) When I plug it in the
standby light on the motherboard comes on, but when I press the power
on button, the only sign I see of anything happening is that the cpu
fan goes on for a split second, and then nothing. Anyone have any
ideas? Thanks

 

[Chris Hill]

hello. I just purchased a matx psu to power a basic asus motherboard
two fans, cpu fan, dvd drive/cd and floppy drive. It's a 320 watt
diablotek, and I think it should be enough.(?) When I plug it in the
standby light on the motherboard comes on, but when I press the power
on button, the only sign I see of anything happening is that the cpu
fan goes on for a split second, and then nothing. Anyone have any
ideas? Thanks

Hmmm, did the board work before? I can't think of anything made today
I'd try to run off such a small supply.

 

[Paul]

hello. I just purchased a matx psu to power a basic asus motherboard
two fans, cpu fan, dvd drive/cd and floppy drive. It's a 320 watt
diablotek, and I think it should be enough.(?) When I plug it in the
standby light on the motherboard comes on, but when I press the power
on button, the only sign I see of anything happening is that the cpu
fan goes on for a split second, and then nothing. Anyone have any
ideas? Thanks

The more info you give, like the hardware inventory, the easier
it is to tell whether it should work or not.

For a basic computer these days, at least one that has that
2x2 ATX12V power connector on it, I'd want at least 12V@15A
rating.

You have to realize, that not all hardware these days, has good
power consumption information. And that is why so many users
end up with power supplies much larger than they need - it is
because you cannot get power numbers for everything.

These are examples of sites that attempt to calculate power.
They tend to err on the high side, which means you are likely
to succeed by using their advice. But the power supply you end
up with, might be bigger than is called for.

This one gives a simple "wattage" rating, when you really need
to know the output current for each DC voltage (like 12V@15A)

http://www.jscustompcs.com/power_supply/

This site offers a spreadsheet style, but the hardware types
are not up to date. I cannot ping the site right now, either...

http://takaman.jp/D/?english

Are you plugging the CPU fan into the motherboard CPU fan
header ? Or is the CPU fan connected to a Molex drive connector ?
The motherboard may be expecting to see a fan RPM signal on
the CPU header, and if the RPM signal is absent, it could shut
down. But based on your description, it almost sounds like the
power supply itself is giving up.

http://www.tigerdirect.com/applicat...&Sku=D15-1026&SRCCODE=PSCANDF&CMP=OTC-PSCANDF

AC INPUT 115V/230V - 60/50Hz
DC OUTPUT +3.3V +5V +12V -12V -5V +5VSB
28A 30A 15A 0.8A 0.3A 2A
320W
Max
Combined

That is enough for a basic low end system. If this is some
kind of "gamer system", then it won't be enough. When you
tell us what is in the computer, that would make it easier
to decide. But the assumption is that the thing really meets
those specs, and it is only $25.

HTH,
Paul

 

[tom]

Thanks for the reply. Its a basic system with onbaord sound and video
card. I'm using two hard drives, a dvd/cd burner, and a tv tuner card.
The cpu fan plugs into the motherboard header.

 

[Paul]

Thanks for the reply. Its a basic system with onbaord sound and video
card. I'm using two hard drives, a dvd/cd burner, and a tv tuner card.
The cpu fan plugs into the motherboard header.

Maybe you could try a few other things first, rather than worry
about the power supply.

Try disconnecting the hard drives and the burner. Pull the TV
tuner card. Remove the video card and the RAM.

The way the computer is supposed to work, is you will get a beep
code if no RAM can be found. If you strip the computer down, so
that the processor is installed, and the computer speaker is
connected, then when it powers up, you should hear a beep code.
The CPU fan should spin and to make the beep code, the processor
is actually executing code to do that. The presence of a
repeating beep code, means the processor is not fried.

You can continue to add and test hardware, until the computer
stops working. The last component connected, could be the
guilty party, or it could be that the PSU has run out of
steam. But at least by adding components incrementally, you'll
have some idea that at least a bit of the gear works.

If your problem is caused by a brass standoff underneath the
motherboard, touching something it shouldn't, you can remove
the motherboard and set it up on the table. The last two
systems I built for myself, I assembled them completely
on the bench, with no computer case. I even booted Windows
while it sat on the table. A thick phone book with cardboard
cover, was placed underneath the motherboard for support.
The only danger with this method of testing, is be
careful not to tug on the video card cable, as the video card
can be pulled out of its slot. So if there are young children
nearby, this is not a good test method. You really need room
to work, where your project will not be disturbed.

BTW: The order of incremental hardware install would be
something like - CPU, memory, video card, keyboard/mouse,
hard_drive and/or CDROM, and so on.

There are some motherboards where you can even start with
no components in the motherboard, and because those motherboards
have a Vocal POST feature, a voice error message on the Lineout
connector, will give you some indication that the motherboard
and PSU work together. But not too many motherboards do that,
so motherboard+CPU is the lowest working configuration for the
rest of the boards.

HTH,
Paul