Hello, following from this thread : http://forum.xbmc.org/showthread.php?t=114353

I have a problem with either my MB or my PSU. Before returning both, I'd prefer if I could just return the faulty hardware. I made a short video of the behavior so if any one can help me, that would be greatly appreciated!

http://www.youtube.com/watch?v=X3xGyjvlKYs

Sorry for the english

To sum it up :

As soon as I plug the PSU into the wall, the fans and the HDD begins spinning.... Then I turn on the PC and the PC behave as normal with some notable exceptions : 4 of the 6 USB ports doesn't seem to work. The LAN port doesn't work either. So, this might be the MB. But...

When I just plug the ATX 24pin power, only the fan are spinning (no power to HDD). But when I connect the cable on the ATX power (so that SATA cable etc have power), the HDD is beginning to spin. So, this bahavior seems to point towards the PSU imho.

I don't have a lot of experience building PC (last one was a 386!), but I can understand

Thanks a lot for your help!

Have you tried the same experiment with the motherboard on a non conductive surface ? It looks like you have a short somewhere...

Well, the MB is in the case, which is on a wood table. Should I put the MB directly on the table?

It might be worth a try and it'll rule out any shorts caused by the case.

ok, I have put the MB directly on the table (no RAM, only the CPU fan connected) and the bahavior is the same.

Also updated the BIOS, etc...

There's a small computer shop nearby, I'll see if they can plug another PSU in the MB.... this will at least discard either the MB or the PSU.

After looking carefully at the video, I noted that your 24-pin power supply connection looks unusual. Does the cable from your power supply have a standard 24-pin connector, or did you rig something up?

If you are absolutely certain that the MB is getting the right power to the right connectors, and have verified that there are no shorts, then the motherboard would be my suspect.

I bought the picoPSU from shop.perfecthometheater.com where I bought my ITX case. This is a 24pin ATX male connector that is plugged directly into the ATX MB female connector. For this troubleshootin test, I've unplugged the SATA, Molex etc power from the picoPSU (see picture #3)



Well, I cant' be sure that there is no short in the picoPSU without disassembling it... :-/ I'll go to the computer shop and see if they can plug another PSU in the 24pin connector.


Picture #1:


Picture #2:


Picture #3:

I have to add that after installing the drivers for the MB, that the USB and LAN back ports are OK.

Okay, sorry I've never seen a picopsu before.

When you said that you unplugged the molex, SATA, etc, did you mean you unplugged them from the power supply?

Does the picopsu respond to all the same control signals as a full-size psu? I mean, when you shut off the computer with the power button, should the picopsu turn it self off? There will be either a 3v or 5v line that stays on, so that it can sense when you push the button to start it up, among other things. But the 5v and 12V power should shut off, at least in a "normal sized" power supply.

no problem!

Yes, I've unplugged them (picture #3) from the power supply (picture #1).



I can turn ON/OFF the PC by pressing the power button on the PC. I'm not sure how the picoPSU respond to this, but my guess is that it should behave like a normal PSU. The 12v is "On" though since both fans are spinning up. So, is it the MB that should cut this power line or the picoPSU that cut it off? I mean with a normal PSU...?

Since the picoPSU is supposed to be fully ATX compliant (I've looked up mini-box's web site), I assume that it will shut down all of the output voltages when you turn the computer off, except for the +5VSB (the one that stays alive so the MB can wake up when you push the power button, etc.). I'd guess that the power supply is not shutting off the 12V output when you turn off the computer. Note that the fan, and hard drives are powered by +12V, and the fans are probably plugged into the motherboard, so they run when there is 12V present on the MB's 24-pin power input. But the picoPSU does seem to turn off the +5V and +3V, which explains why your computer does turn on and off.

Looks like your best bet is to take the whole rig to the local computer store and test the motherboard with a power supply that is known to be good. If it works the way it should, then the picoPSU should be returned for a warranty exchange.

If you have a meter, you can check the picoPSU directly to see if it is supplying +12V when it is off.

Great, thanks for the explanation! I now know more than this morning!

The MB is at the computer shop and I shoud have the results later today. While the MB is gone, I plugged the chassis fan on the PSU (through the molex connector) and guess what? The chassis fan starts spinning! So, I'll wait for the results, but my guess now is that the picoPSU is faulty.

Thank for your help, I'll report back with the results!

Is that a genuine picoPSU btw? It doesn't look like any of the models on www.mini-box.com. I recall another thread on the board with another member having problems with a similar PSU. There have been reports of fakes.

I don't think it's genuine, but the shop seems to do serious business (http://www.shop.perfecthometheater.com/). I've contacted him to see how we proceed for an exchange or refund. We'll see how serious they are I guess!

Just came back with the MB from the repair shop. With their PSU, the MOBO is acting the same way. So, I'll RMA the MOBO hoping it's the only defective part! :/

That makes no sense. When the power supply is turned off by the button on the computer, it should NOT be outputting any 12V current. Period. Further, power on and power off do not effect the different voltage supplies separately. When the MOBO sends the power supply the signal to turn off, it is only one signal and the whole PSU should shut off.

Ah men... I guess I'll just send back both! :/ Rather confused...

Ok, so just received a new picoPSU from perfect home theater. It works! So it was indeed the PSU that wasn't able to shut down th 12V rail.

The picoPSU from Perfect Home Theater is made by Wesena, if anyone wonder.

Thanks for your help everyone, I now have a working HTPC. But far from silent! Just ordered a Noctua 80mm case fan to replace to stock one.