Power Supply/Motherboard Issues

vbimport

#1

I recently acquired a PC from my friend that I was hoping to start using as a spare PC. I’ve been having problems getting a Corsair HX520W power supply unit to boot the rig. Here are some of the rig specs:

Gigabyte GA-K8N51GMF-9 motherboard
AMD Athlon64 3500+
1 GB RAM
ATI Radeon X550 256 MB
Hairong ATX-550W PSU

For some strange reason, it all boots just fine with that $20 power supply in it, but will not even load up the BIOS when I connect the superior Corsair power supply.

I know that the Corsair power supply works fine because it boots this rig every day:
Abit UL8 motherboard
AMD Athlon64 3500+
1 GB RAM
ATI Radeon 9550 256 MB

Even if someone can just tell me why this combo will never work, I’ll be satisfied - it’s the not knowing that’s killing me!

Cheers.


#2

Sounds like a grounding issue to me something is grounding the mobo out and the
Corsair power supply isn’t letting it boot up. I had a experience something similar
to what you are having and it turned out to be one of the standoffs was grounding
the mobo out.

Yep a cheap no name PS would still boot it up but the Corsair with its excellent
grounding protection would not let it boot at all but it did start right up after the
standoff that was shorting the mobo out was removed.

I see no reason for it to not boot other than it having a short somewhere. :confused:


#3

Thanks for the reply getit29.

One thing I did notice is that when I connect the power cord to the power supply unit and the PSU is switched on at the back, the CPU fan will slowly spin two or three times before I actually power up the PC.

Then, when I power the PC up, the CPU fan comes alive up and the hard drive powers, but there is no picture to the monitor. I also get repeated beeping from the motherboard.


#4

Try clearing the CMOS (with the power unplugged). But do like getit29 was saying, maybe remove the MB and check all the standoffs.


#5

Thanks for the replies.

What exactly would I be looking for when I take the motherboard out?


#6

The little brass standoffs (the things the MB sits on), either one might be out of place as in it might be filling a hole that doesn’t correspond to a hole in the MB. It could also just be poorly aligned and touch a bare metal spot on the MB. They are supposed to touch a ground on the MB (negative), that is on the MB where the screw goes in the hole on the bottom side there is a ring of bare metal that is an electrical ground.


#7

[QUOTE=masta_blasta;2557479] I also get repeated beeping from the motherboard.[/QUOTE]Your motherboard tries to tell you what’s wrong. --> http://en.wikipedia.org/wiki/Beep_code

–> http://www.pchell.com/hardware/beepcodes.shtml

Michael


#8

I wonder if the problem is -5v, which became optional in ATX 1.2, prohibited in ATX1.3 (but still included in many old design cheapies).

Or the switch from ATX 1.x to ATX 2.x, where the 12V was emphasized over the +5V, leading to cases where cheap PSUs with weak 12V and old style 5V, may work better on older 5V heavy boards.

My guess is the board wants -5V for something, and the Corsair follows the letter of current ATX and does not have it!


#9

[QUOTE=Matth;2561923]I wonder if the problem is -5v, which became optional in ATX 1.2, prohibited in ATX1.3 (but still included in many old design cheapies).

Or the switch from ATX 1.x to ATX 2.x, where the 12V was emphasized over the +5V, leading to cases where cheap PSUs with weak 12V and old style 5V, may work better on older 5V heavy boards.

My guess is the board wants -5V for something, and the Corsair follows the letter of current ATX and does not have it![/QUOTE]

Switching power supplies can be tricky. I would check the voltages with a volt meter. Compare the readings to the cheaper one and see where the difference lies. If there is none, then it is probably switching off because of a bad ground.