Computer won't power up.

[Amaron]

First off my computer

Intel Core 2 Duo E8500
Gigabyte EP45-UD3P
Radeon HD 4870
4 DDR2 800 1 gig sticks
2 sata hard drives
1 cd/dvdr
550w AMI phoenix psu

I tried searching on this but no luck so far. The system was running using an nforce 4 board with an AMD X2 before so the only thing thats new are the CPU and the mobo.

I plugged everything in and tried to power up and nothing happened. No fan spins or anything.

So I checked all the connections and double checked them and they are all good. First thought after that was maybe theres too much power draw somehow so I pulled out the video card. That was no good either.

After doing that I used a jumper to short the power switch pins on the motherboard. That didn't do anything either. After messing with all this though I noticed that when the PSU is turned on suddenly my WD MyBook USB drive lights come on (even though its plugged into the power strip).

So from that I'm guessing the PSU is turning on at least because somehow power is getting into the system and going to the USB ports on the mobo.

Beyond that I'm at a loss now. I don't even know what situations can cause the system to not power up like this. Any help is highly appreciated.

 

[pcgeek11]

Test the power supply:

http://www.overclock.net/faqs/...-power-supply-psu.html

read the yesllow wire to black with a multimeter it should read~ +12 volts
read the red wire to black and it should read ~ +5 volts
read the orange wire to black and it should read ~ +3.3 volts
read the blue wire to black and it should read ~ -12 volts
read the blue wire to black and it should read ~ +5 volts

Pinouts:
24 pin ATX Connector: http://pinouts.ru/Power/atx_v2_pinout.shtml
20 pin ATX Connector: http://pinouts.ru/Power/atxpower_pinout.shtml


pcgeek11

 

[Ausm]

Make sure you new mobo isn't grounding out in the case. Thry this.

1)Take the mobo out and put it on a nonconductive surface

2)Leave the CPU,heatsink,RAM and video card on the board

3)hook up the soft power on switch

4)hook your monitor to the video card

5)fire it up

 

[Amaron]

Ok I tested the PSU with the listed method and it powered up fine and all the voltages read fine.

I took the mobo out of the case and put it on a nonconductive surface with just the CPU in it and plugged it back in but it wouldn't power up still.

I can only surmise that it's the mobo at this point. Is there anything else I should check before I RMA it though? Also is this just a sign of a faulty mobo or would it act like this if it got to much static somewhere?

Anything anyone can think of would be helpful.

 

[mpilchfamily]

Static could have caused it sure. But really the details don't matter. Fact is the board is dead. It can be claimed as DOA and a new one can be sent too you.

 

[Amaron]

I tried plugging in the old motherboard again and hooking everything up but now that's not working either. Everything is exactly as it was before but it won't start up. The power switch is not broken and I definitely grounded myself properly when doing this stuff so I'm very skeptical both mobos are bad.

I'm most skepitcal now that its the PSU. The voltages I get are approx correct when I tested it by powering it up itslef (5.22 on 5v 12.25 on 12v etc). Is it still possible something is wrong with the PSU even though it passed these tests? I just can't figure out what else could be wrong otherwise.

Edit: Just an update here but I successfully got it to power up the old motherboard sans the 4870 with a crappy PSU from another computer. So I can only surmise it was indeed the PSU since I tried this setup with the old one as well. Thats for all the help all.

 

[greenbean]

Yes your PSU is probably bad. Just because you see a voltage on the pins of your PSU with a multimeter does *not* mean that the PSU will maintain anything near those voltages when hooked up. Discrete components in the PSU can fry but still output sane voltages in an unloaded test. You need a tester that fully loads the PSU if you want to know for sure.

 

[logicmaster2003]

from the pinout.. http://pinouts.ru/Power/atx_v2_pinout.shtml

i want to ADD something since I'm on the same boat - the GRAY wire "PWR_OK" (pin 8) should read 5 volts even if its on stand-alone test (jumper pin 16 to ground) ? cuz im reading something like 95mv.
Please do the same test and lets see if you're getting the same voltage level.

 

[Amaron]

I already threw that PSU out but the PWR_OK reads like it should be an on/off thing. If you powered up the PSU and that one is reading .95mv that should mean the power supply is telling the mobo that its not working correctly.