Just biuld PC - Advice wanted - won't start up

[rob1234]

Just built a PC. It won't start up. The all fans (PSU, CPU and case) just turn momentarily then system stops. Motherboard LED remains lit, no signal to monitor.

Spec

Asus A8S-X motherboard
AMD Athlon 64 3200+ processor
Memory kingston 512 MB (model as per motherboard guide).

Any advice welcome.

Thanks

Rob1234

 

[daveola]

I just worked on a computer yesterday for a guy that had the exact same problem and it was an AMD 2600+. This could be a few different things. The first thing I did was unplug the PSU from the board and plug it in to my PSU tester. The tester showed that the PSU had a bad -5v rail. I put a new PSU in the tower and the computer fired right up. Make sure all your power plugs are plugged in correctly. Your board has a 4 prong plug that attaches to the board by the CPU also. If it is not plugged in the machine wont work. I would feel pretty comfortable that your problem is the PSU or somewhere in the PSU connection to the board. You didn't list the brand and power output of your PSU so I can't tell if you have a good one or not. AMD's love lots of power so make sure you have a good PSU. If it turns out that your PSU is fine then start looking at other components you have plugged in to the board. This is hard to figure out if you dont have other parts to switch for testing. Hope you get it working.

 

[sruane]

The last time this happened to me was because the default voltage on the memory bus was insufficient. I had to boot with a cheap stick of less demanding ram and raise the voltage.

 

[Fulmar]

The tester showed that the PSU had a bad -5v rail. quote]

To the best of my knowledge and from what I've read and experienced, the -5V rail isn't used anymore - thus thats why it showed up failed. Like I bought an Aprevia PS tester cheap off newegg just in case and tried it on my power supply for my new reg and it said -5V failed but reading this forum and the newegg comments said that it will come up failed because its not used anymore.

_______________
NewEgg Reviewer:
Pez

Tech Level:average
Ownership:1 month to 1 year
11/12/2006 8:47:23 PM Good, But


Pros: Easy to use

Cons: Newer power supplies may not even have a -5V rail, yet the instructions on this unit will flag a missing -5V rail as defective. The -5V was dropped from the Intel standard several years ago. As long as you know that, the tester is OK. The bottom line for the average user is does it tell you whether your PS is good or bad?

 

[sirheck]

Just built a PC. It won't start up. The all fans (PSU, CPU and case) just turn momentarily then system stops. Motherboard LED remains lit, no signal to monitor.

Spec

Asus A8S-X motherboard
AMD Athlon 64 3200+ processor
Memory kingston 512 MB (model as per motherboard guide).

Any advice welcome.

Thanks

Rob1234

doublecheck all of your front panel connects.

 

[daveola]

Well, whether it is used anymore or not, all of the other rails tested fine and adding a new PSU fixed the problem.

 

[rob1234]

Thanks for the replies! I appreciate it!

Still doing the same - Just built a PC. It won't start up. The all fans (PSU, CPU and case) just turn momentarily then system stops. Motherboard LED remains lit, no signal to monitor

My power supply is the following:

ENLIGHT GPS-350EN-102 A

Just tried a voltmeter across the 4 pin CPU power supply (12V - ground). Couldn't get a voltage reading - do all power rails power up straight away? Wasn't get very good readoings on the 24 pin socket either.


Other bits
Asus A8S-X motherboard
AMD Athlon 64 3200+ processor
Memory kingston 512 MB (model as per motherboard guide).
Radeon X550 video card

 

[cmptrdude79]

Did you jump the signal pin to actually fire up the power supply? I don't remember exactly which pins it is off-hand (I'm in meetings all day today, not in the shop), but if you don't jump those you will only have certain leads with power to them. Should be able to find which pins by googling "manually start ATX power supply".

I'll check back when I get home and post which leads to jump to fire it up.

-J

 

[daveola]

It will be the GREEN and any BLACK together to start an ATX supply

 

[DrNeil]

if the motherboard isn't seated properly and is touching the case that can cause problems. You could try taking it out and putting it back in again.

 

[rob1234]

To conlcude the story:

It was a faulty power supply. I shorted the green and black together to switch it on and then tested the voltage across each pin to ground. Found the 24-pin connector was OK but the 4-pin CPU lead did not have a sustainable voltage (it did flick up to ~12V momentarily when I turned the power on though).

Anyway I replaced the power supply and its all working fine now. I'm writing this from the computer in question.

Thankyou for all the advice!

Rob1234