effect of underpowered psu?

[dboy]

Would an underpowered psu result in NOTHING happening at all? Here's the situation...

Got an old p1 case w/ a 145 watt psu in it. Picket up an Asus k7m mobo and 500mhz Athlon off the fs/ft board here. Hooked everything up, nothing happens when I push the power button. If I connect the atx plug from the psu to the old p1 board and hit the pwr connector, things start spinning.

Now, the k7m manual says not to use anything under 200w, but this was all I had so I gave it a shot before I go toss money on a new psu. Would being that far underpowered give nothing like I'm seeing, or should there still be SOMETHING happening (at least psu fans spinning). Just trying to see if I've got a dead mobo here before I spend on a psu.

 

[iJR]

A system with a PSU that isnt powerful enough will do some many wonderful things. Not POSTing is one of them.

I have had a system seem to work fine but as soon as you put some load on it, it dies.

Best thing to try is to see if someone will lend you a PSU to test.

 

[tboneuls]

Definetly sounds like a PSU problem. Borrow one, find one, but try another (larger) before buying a new one.

 

[amdskip]

I bet something else is wrong. Just try booting without and cdroms, hard drives, extra pci cards installed and see what happens. I've ran a 1700xp on 145 w power supply out of a gateway computer and it didn't break a sweat.

 

[Unforgiven]

hit the store and get yourself a higher watt power supply and test it out. typically local computer shops are very cool about power supply returns if you explain to them what you are trying to do. start there, then move onto troubleshooting the motherboard.

 

[TheCorm]

A Generic 250/300W would power that system no probs.

 

[dboy]

I just ran to CompUSA and picked up their cheapo 250w for 25 bucks... give it a try tonight and hopefully things will be happy!

 

[iJR]

let us know what happens when you try it

 

[dboy]

Ok, here's the latest. The 250w compusa PSU didn't do anything either. Tried it in another mobo, worked find. Noticed that it was rated for 15A on the 5v line, and the k7m manual say you should have 20. So, pulled apart one of my Dells (a p4) and it's psu was rated for 22A on 5v, so I tried that. Still nothing at all.

Is there anything else I should try before I assume it's a dead mobo? It's not the physical switch itself, I tried connecting it to another pc and it worked fine. Also tried hitting the pins on the mobo w/ a screwdriver, nothing.

 

[Unforgiven]

are you sure the motherboard isnt grounding out against the side of the case by any chance? if i were you i would take the motherboard out and put it on an anti-static sheet outside the case and see if that helps. if that doesnt work, make sure that you have the correct connections from the case (reset switch, hd led, etc) set up correctly on the motherboard. ive had boards that freak out and wouldnt work unless i had all of those properly connected.....good luck and keep us posted!

 

[dboy]

Tried taking the mobo out of the case. First tried it "loaded" - cpu, ram, etc all hooked on. Nada. Took off everything - I had just bare mobo w/ psu connected. Nada. Tried hooking up various items, still nada. Is there any posibility left besides dead mobo?

 

[iJR]

it really doesnt look like it.


If you leave everything out, not even RAM, does it beep at you?

 

[alm4rr]

check the capacitors for crusty material and a swollen look to their tops