Computer not turning on - troubleshooting help

[redsky009]

I've just opened my box up to install a couple of sticks of RAM and swap out my old gfx card for a new Powercolor HD4870 1Gb.

What I did:
-Took out the old card and moved my sound card (creative X-Fi) to another PCI slot to make room for the HD4870
-Inserted the HD4870 and plugged in the two 6 pin power connectors
-Clipped the RAM in

Then I plugged the power cable back in to the Corsair HX520 and flicked the switch. The light on the mobo comes on, but nothing else happens. No fans, no beeps, nothing.

I've checked through the power connections and they all seem fine. I reseated the HD4870, the RAM and the X-Fi cards and still nothing. The X-Fi has a light on the back which doesn't turn on when the mobo light comes on, but I can't remember whether this turns on after you turn the PC on not.

Any ideas for more troubleshooting? What would you suggest the next things to try are?

[Webby]

Change the graphics card back to the old one and see if it boots, if not take out the new RAM and see if it boots if it does put the new graphics card back in and try again, if it boote replace the old memory with the new try again, if it boots go into the BIOS and up the FSB and MCH (northbridge) voltages a notch, replace the ram and reboot.

That should test pretty much every possibility of whats wrong from a new hardware perspective.

[redsky009]

Change the graphics card back to the old one and see if it boots, if not take out the new RAM and see if it boots if it does put the new graphics card back in and try again, if it boote replace the old memory with the new try again, if it boots go into the BIOS and up the FSB and MCH (northbridge) voltages a notch, replace the ram and reboot.

That should test pretty much every possibility of whats wrong from a new hardware perspective.

Thanks, will go and try that now and let you know how it goes...

[redsky009]

No joy

Tried swapping things back to the way they were, but still the same result. The fan in the power supply doesn't come on either...

I've tried taking everything out (gfx, xfi, new RAM) and still the same result

I would say it was a blown power supply or motherboard, but the mobo light comes on which shows that there is power getting there and it's not completely fried...

[Webby]

Hmm yeah sounds like PSU or Mobo, don't suppose you happen to have another PSU kicking around you can try?

[redsky009]

Hmm yeah sounds like PSU or Mobo, don't suppose you happen to have another PSU kicking around you can try?

Might have an older 300W supply knocking around but don't know if that will have enough juice...

Don't know how the power supply could have blown as I didn't really do anything to it. Hmm, this sucks royally

[Webby]

try the old PSU, using the old graphics card, unplug everything thats not vital to boot so hard drives, DVD, soundcard, only 1 stick of ram all were aiming for here is to get it to post.

[redsky009]

try the old PSU, using the old graphics card, unplug everything thats not vital to boot so hard drives, DVD, soundcard, only 1 stick of ram all were aiming for here is to get it to post.

OK will give that a go tomorrow when I'm not tired, thanks for the help dude

[ackrite26]

Tried resetting CMOS??

[peterb]

Tried resetting CMOS??

The machine isn't getting to the point where it even looks at the CMOS data!

It is worth double checking all the plugs and especially the one that connects the front power button to the mobo - if that has been displaced during your upgrade, that would give the symptoms you describe (as I understand them)

Do you have a floppy disk drive and if so, was that unplugged? (I mention this because I have seen instances where the floppy plug is displaced and shorts the power rail to ground).

The fact the fan on the PSU isn't working tends to point to that as being faulty, but you can only really test that by substitution. However a minimal system would be be powered by the 300 W you have lieing around and give some POST indication - even if only beeps on the speaker.

[redsky009]

I tried unplugging and reconnecting the 12V and the other power cable to the motherboard but that didn't help. What I'll try when I get home is unplugging all the power parts and then reconnecting them carefully.

It might just be that it's the connector from the power button to the mobo as this is near the PCI slot where I moved my sound card. Is there a way of testing this easily? That would be the cheapest solution!

I'll also try the other power supply and cross fingers...

[Webby]

I tried unplugging and reconnecting the 12V and the other power cable to the motherboard but that didn't help. What I'll try when I get home is unplugging all the power parts and then reconnecting them carefully.

It might just be that it's the connector from the power button to the mobo as this is near the PCI slot where I moved my sound card. Is there a way of testing this easily? That would be the cheapest solution!

I'll also try the other power supply and cross fingers...

If the power switch connector is dislodged then you just need to push it back on, if the switch is broken (highly unlikely I would have thought) then touch a screwdriver across the two jumper pins and this will start the PC (if that was the problem.

[redsky009]

Update: thanks for everyone's help, managed to get it up an running eventually!

Tried this: http://www.houseofhelp.com/forums/sh...ad.php?t=63991 method for testing the PSU and it all worked ok, so I went one by one through all the cables and found that the fornt panel power connector wasn't quite connecting properly with the pin on the mobo. Once this was fixed, it all booted up nicely. Just going to give Crysis warhead a whirl now

[Webby]

Glad you got it sorted