Need advice on which component is at fault

[farmercal]

I am posting this from home on my old system at home and have to go to work in a few minutes and can't respond from work so I can only read your suggestions.

I have a 6 month old system I bought used form the For Sale/Trade forum. System ran fine when I tested it out and everything was fine and dandy. I set it aside while I built my new computer enclosure and when I put it in the new enclosure it ran for about 2 minutes and then rebooted. I then attempted to power up numerous times and it runs for about 20 seconds and then shuts down. Here are the specs:

Asus A8N-SLI Deluxe motherboard
AMD 64 4000+ processor
Corsair XMS 3200 RAM (2GB)
Zalman 9700 CPU Cooler
Thermaltake north bridge cooler
Corsair 520W Power Supply
Sapphire 1650 Pro PCIE video card

- The power supply is new and was used in my old rig and ran just fine.
- The memory was used in my old rig and ran just fine and my old memory Corsair 3500 had same results in new build
- Using arctic ceramique thermal grease (applied twice just in case)
- Neither the north bridge or the CPU gets warm during time on so I doubt it's a heat issue.

This leaves motherboard or CPU. Which would you think is the culprit here?

Note: I don't have an extra CPU or motherboard to shotgun to find fault, so I will have to purchase one or the other to do that.

Any ideas? I will read responses at work but cannot post until I get back home. Thanks.

Update: Just for kicks, I decided to disconnect the 12V ATX connector from the motherboard to see what would happen. Well it turned on and stayed on for minutes but with no video. Then I plugged it back in (at this point the motherboard and power supply are on my table, not in the case) snugly since the motherboard wasn't in the case and now the system runs just fine. Thanks for all the suggestions anyway. I don't know why I checked that plug, just had a hunch I guess.

 

[Puffnstuff]

Did you double check your hsf fan to make sure that it's plugged into the correct header on the mb?

 

[yh125d]

yeah, if it is plugged into a case fan header, and theres nothing in the CPU header, it won't boot

 

[bruceb]

I agree .. it sounds like the CPU Fan is not connected to the the CPU Fan Header ... systems will not boot / run
without a cpu fan

 

[sjandrewbsme]

It sounds like a heat issue to me.

You said the HS doesn't get hot - that may not indicate anything. If it's not making proper contact with the CPU IHS then it wouldn't heat up (very much) - the CPU would get extremely hot though.

Check the same thing with the NB heatsink. I know I have an A8N-SLI for sale and when I packaged it for shipment, I took off my aftermarket NB cooler (Zalman passive) and replaced it back with the stock cooler (8k rpm fan - loud and annoying). It's possible the seller did the same and didn't install the NB HS correctly. Again, the chipset below could be getting white hot if it's not making proper contact with the HS above. What's more is that you would touch the HS and note that it's cool.

 

[bruceb]

Just looked at the mb manual .. you have a total of 5 fans that all must be connected or that board will not boot up.
Check all of them are connected and to the correct headers.

 

[ch33zw1z]

Since when are any fans, other than cpu fan, required to boot?

 

[bruceb]

I may be wrong, but according to the mb manual, it looks they make a big deal
out of explaining all the fan connectors. And I stand by my remarks. The OP
most likely either: Forgot to connect the CPU Fan / The CPU Fan is on the wrong
MB Header and BIOS does not see it / The CPU Fan is Defective .. it may run, but
not put out an RPM Signal

 

[farmercal]

First of all the CPU fan is connected to the CPU header on the motherboard.
I tried hooking up fans to all the fans connections on the motherboard - same problem
I re-applied thermal grease to the CPU and the Northbridge cooler - same problem

It is either the motherboard or the CPU causing the problem. It alway boots and gives a confirmation beep then before I can get the BIOS screen to pop up it turns off. All the fans start up and everything runs smooth as silk for about 20 seconds and then off.

I have been putting systems together for some time and never saw anything like this.

 

[Puffnstuff]

Do you have another ps you could use in the system just to make sure that the ps is not bad? Also before you installed the new mb did you make sure that the standoffs were in the right places? If one is grounding the mb out it would shut down.

 

[GuitarDaddy]

I would remove the motherboard from the enclosure and connect just CPU, GPU, and ram and test it that way first. The symptoms indicate a possible short IMO.

What I'm hearing is everything ran fine until you moved it to the new enclosure, which points to either shorting or something is not connected correctly. Highly unlikely anything went bad with mobo or CPU while sitting idle.