Problem with 12V 120W ATX PSU

whitty · Post by **whitty** » Tue Mar 30, 2010 4:50 am

I recently purchased a 120W PisoPSU style setup from ebay but even though it starts the fans and the LED turns on, it won't activate the display.

The PC is a Celeron 1.2GHz that I got to run on about 40W at idle, and have all the drives disconnected. It had an AGP card but I tried it with a PCI graphics card and still no juice. When I connect the old ATX PSU it boots fine.

My power meter shows 38W with the original PSU and 36W with the 12V brick + 120W PSU. I checked the 12V and 5V on the drive power connector, and 3.3V on the motherboard plug and it seems ok.

Has anyone had similar trouble with these units? I read something about resetting the CMOS and trying again but I got no love.

I've contacted the seller, but hopefully I can get it working instead of returning it.

Vicotnik · Post by **Vicotnik** » Tue Mar 30, 2010 5:23 am

I wonder if it could be that the CPU draws power from the +5v rail and that the Pico is to weak. The specifications says 6A max load, 8A peak on the +5v rail for the PicoPSU 120W.

greenfrank · Post by **greenfrank** » Tue Mar 30, 2010 6:17 am

pico 120 (if not defective) can feed your rig. I have a pico 120-wi with an Athlon II x2 system, and works perfectly.

Have you checked the power brick instead? Maybe this is the responsible.

whitty · Post by **whitty** » Tue Mar 30, 2010 2:08 pm

I've used 2 power bricks and they're both putting out 12.3V when the box is running. I'm not sure how it could be drawing 36W through the power meter if it wasn't supplying the correct voltages.

Vicotnik · Post by **Vicotnik** » Tue Mar 30, 2010 2:30 pm

Do you have another system available that you could test with the PicoPSU? What motherboard are you using?

whitty · Post by **whitty** » Wed Mar 31, 2010 1:50 am

yeah i'll have to drag something out of the shed and see what is there. the seller said i need a bigger brick, but it's only drawing 36W and the voltage is still 12.3V so I'm not sure how a bigger brick will make a difference.

the mobo is an abit vh6t (from memory)

Vicotnik · Post by **Vicotnik** » Wed Mar 31, 2010 10:21 pm

See if you can reduce the power draw of the CPU and/or other things. Start with a minimal number of components. Just the motherboard, CPU (underclocked via jumpers or BIOS settings), one stick of RAM, the PCI graphics card and a keyboard.

I think it's a high draw on the +5v rail at startup. The Pico is built for more modern systems which uses the +12v rail to power most things.

You don't need a more powerful brick.