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No boot, no mobo LED, no beeps, will not power off, fans on

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July 24, 2010 7:02:22 PM

I've built a new system and to my horor I got a no boot upon startup, as well as no beeps. All the fans were operating, as was the CD drive, I believe I heard the hard drive spin up as well. I got no light on the mobo and could not power off the system (had to turn it of at the wall, the Bewlkin sugre protector should have prevented damage). No USB power either. I've tried reconnecting everthing, hence I think the motherboard is dead. Might be a PSU issue though, I can't tell. I'd be grateful for any sugesstions helping to pin down the issue. I used appropriate EPS protection in installation. System specs below,

A6GMV Foxconn motherboard
AMD 955 @ 3.2 ghz
Sapphire HD 5850
750W Modular PSU 80+ Dual 12V V2.2 High Efficiency
Coolermaster 330 case
Seagate barracuda 7200rpm 500gb
samsung CD drive

a b B Homebuilt system
July 24, 2010 7:38:19 PM

NO light on motherboard means DOA motherboard.
July 24, 2010 7:55:55 PM

Is it possible that the PSU caused the mobo to die? The PSU is brand new and although powercool might be slightly dubious, it is one of their "better" power supplies.
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July 24, 2010 8:13:27 PM

I've done everthing on the list but trying to reset the CMOS, is it worth a shot? How strongly would you reccomend swapping out the PSU, I'd rather not since I'm on a tight budget (I could only afford a 5850 because I won a voucher in a compotition)? Could you perhaps reccomend any decent budget power supplies if your adament my current one will cause issues? Thanks for the help guys.
a b B Homebuilt system
July 24, 2010 8:30:07 PM

It's not the power supply because it is powering everything else but the motherboard.

Sorry Jim - it's dead.

mr pi said:
Is it possible that the PSU caused the mobo to die? The PSU is brand new and although powercool might be slightly dubious, it is one of their "better" power supplies.

July 24, 2010 8:35:48 PM

Thats not too bad... I thought a £34 Foxconn motherboard sounded a bit too good to be true.
a b B Homebuilt system
July 24, 2010 8:43:37 PM

That's what RMA's are for
a c 82 B Homebuilt system
July 24, 2010 9:52:19 PM

xxsk8er101xx said:
It's not the power supply because it is powering everything else but the motherboard.

Sorry Jim - it's dead.


Flawed logic. A power supply can go bad on an individual rail. Like the CPU power.......+12v rail.

If you can try it with another power supply it is not a bad idea. It could very well be the MB but there is no way to rule out the PSU by saying that "everything but the motherboard works". If you can borrow one or take that one to a computer shop they can test it for you.....not sure about "over there across the pond" but locally here in the US some shops will test a PSU for you for free.

If you have to replace it look for Corsair, Seasonic, Antec, PC Power and Cooling or Silverstone units. A HD5850 would need 450 to 500 watts from one of these manufacturers.

There are some very good cheaper units from Gigabyte or Asus that would be a huge step up from Foxconn.
July 25, 2010 10:40:05 AM

Testing the PSU could be a real problem for me, the nearest harware shop is an hour's drive and they charge extortionate rates. Will swap out the PSU for peace of mind... I heard OCZ were reliable, what about an OCZ 600W StealthXStream? I can get one of those for £54 (80$ or so).

Gonna try to get the motherboard replaced, no reason why a new one shouldn't work.
a c 122 B Homebuilt system
July 25, 2010 2:13:01 PM

xxsk8er101xx said:
NO light on motherboard means DOA motherboard.

:non: 
No light on motherboard can mean:
No power into the computer
A DOA motherboard
A DOA PSU, particularly the standy power supply inside the PSU.

The best way to test the PSU is by substituting a known good PSU. Brand new, out of the box PSU is not known good. Next think you can do is borrow a DMM and measure the outputs of the PSU.

Measure between the colored wires and either chassis ground or the black wires. Yellow wires should be 12 volts. Red wires: +5 volts, orange wires: +3.3 volts, blue wire : -12 volts, violet wire: 5 volts always on. Tolerances are +/- 5% except for the -12 volts which is +/- 10%.

The gray wire is really important. It should go from 0 to +5 volts when you turn the PSU on with the case switch. CPU needs this signal to boot.

You can turn on the PSU by completely disconnecting the PSU and using a paperclip or jumper wire to short the green wire to one of the neighboring black wires.
http://www.youtube.com/watch?v=5FWXgQSokF4&feature=yout...

This checks the PSU under no load conditions, so it is not completely reliable. But if
it can not pass this, it is dead. Then repeat the checks with the PSU plugged into the computer to put a load on the PSU. Here, you can carefully probe the back of the main power connector.

From the symptoms that you posted, my guess is that the violet wire will read 0 volts and the standy power supply inside the PSU is dead.

July 25, 2010 4:59:20 PM

Jsc was pretty close, I found out that one of the local PC world store's had a little gizmo to test PSU outputs (No charge luckily). Long story short, the 4 pin extension to the 20 pin going into the motherboard wasn't supplying any power. Gonna go for the 600w OCZ I mentioned earlier, unless someone has a better reccomendation. However, I'm not entirely sure this could explain my lack of USB power and an inability to shutdown, hence I'm considering swapping out for a Gigabyte mobo while I'm at it. Don't suppose that not being able to shutdown could be due to a case defect? It would seem odd that the wiring would prevent shutting the system off, yet allow it to turn on.
a b B Homebuilt system
July 25, 2010 7:41:19 PM

Right that's why it powers everything else just not the motherboard.

??? freak

anort3 said:
Flawed logic. A power supply can go bad on an individual rail. Like the CPU power.......+12v rail.

If you can try it with another power supply it is not a bad idea. It could very well be the MB but there is no way to rule out the PSU by saying that "everything but the motherboard works". If you can borrow one or take that one to a computer shop they can test it for you.....not sure about "over there across the pond" but locally here in the US some shops will test a PSU for you for free.

If you have to replace it look for Corsair, Seasonic, Antec, PC Power and Cooling or Silverstone units. A HD5850 would need 450 to 500 watts from one of these manufacturers.

There are some very good cheaper units from Gigabyte or Asus that would be a huge step up from Foxconn.

a b B Homebuilt system
July 25, 2010 7:45:18 PM

Ya one of those rare occasions where the 24pin power is bad. Honestly you need to play the lotto.

mr pi said:
Jsc was pretty close, I found out that one of the local PC world store's had a little gizmo to test PSU outputs (No charge luckily). Long story short, the 4 pin extension to the 20 pin going into the motherboard wasn't supplying any power. Gonna go for the 600w OCZ I mentioned earlier, unless someone has a better reccomendation. However, I'm not entirely sure this could explain my lack of USB power and an inability to shutdown, hence I'm considering swapping out for a Gigabyte mobo while I'm at it. Don't suppose that not being able to shutdown could be due to a case defect? It would seem odd that the wiring would prevent shutting the system off, yet allow it to turn on.

a b B Homebuilt system
July 25, 2010 7:47:50 PM

Right it can mean God hates you too but sometimes the easiest resolution is the correct one until further examinations are done. The motherboard could still be bad.

Kids and always wanting and trying to be right. Little do you understand that it doesn't matter.

jsc said:

No light on motherboard can mean:
No power into the computer
A DOA motherboard
A DOA PSU, particularly the standy power supply inside the PSU.

The best way to test the PSU is by substituting a known good PSU. Brand new, out of the box PSU is not known good. Next think you can do is borrow a DMM and measure the outputs of the PSU.

Measure between the colored wires and either chassis ground or the black wires. Yellow wires should be 12 volts. Red wires: +5 volts, orange wires: +3.3 volts, blue wire : -12 volts, violet wire: 5 volts always on. Tolerances are +/- 5% except for the -12 volts which is +/- 10%.

The gray wire is really important. It should go from 0 to +5 volts when you turn the PSU on with the case switch. CPU needs this signal to boot.

You can turn on the PSU by completely disconnecting the PSU and using a paperclip or jumper wire to short the green wire to one of the neighboring black wires.
http://www.youtube.com/watch?v=5FWXgQSokF4&feature=yout...

This checks the PSU under no load conditions, so it is not completely reliable. But if
it can not pass this, it is dead. Then repeat the checks with the PSU plugged into the computer to put a load on the PSU. Here, you can carefully probe the back of the main power connector.

From the symptoms that you posted, my guess is that the violet wire will read 0 volts and the standy power supply inside the PSU is dead.

!