New mobo - won't power up

I have to ask
How was the MOBO tested, did they use all your hardware, including your PSU?

You also posted you tested your PSU.
What was your voltage readings when you tested, idle & load and did they fluctuate?

Ya know I'm still thinking, Crap PSU

You might check the PSU cables for wear or break's in the insulation and or wire
Also inspect the connecting points/pins for corrision including the mobo's connecting points

 

Thanks, ASUS. Yes, the shop had the entire machine and checked everything they could. (couldn't test the CPU because they had no known-to-be-good mobos with socket 754) Don't know what kind of test protocol they used but it required a full day to run. They (and I) also checked PSU voltages while idling and under load. I noted no difference in voltages between the 2 states, and it appeared to be steady. I've tried wiggling the cables while power's applied, with no change. But if power is getting to the board without being controlled by the power switch, wouldn't that indicate something other than the PSU? I'm beginning to realize, though, that troubleshooting computers doesn't always involve logic.
Thanks, ASUS; I appreciate the use of your expertise.

 

My son is having exactly the same problem with a similar set of equipment:

Mobo: ASUS K8N
CPU: Athlon 64 3200+ (socket 754)
PSU: No Name 480 W
RAM: DDR 512 no name one stick

It would be great to figure out what the problem is. He replaced the mother board with an identical one with no change. He's now replacing the CPU with not too much hope of a fix after reading this thread.

The computer functioned for over a year with no problems until a second hard drive was installed. Newest hard drive uses SATA, the old one uses IDE. The computer worked for a week fine with both HDD's working.

Our original suspicion was a power surge, however, the computer was turned off.

All the equipment has been switched out with working equipment for testing except for the brand new mobo and the old CPU and the RAM.

Thanks.
abri

 

I'm sure someone will correct me if I'm wrong, but I think a power surge could do damage even with the machine shut off as long as it was plugged in. However, my first reaction is that the mobo doesn't like the idea of the IDE and SATA HDDs in concert. I have no experience to back that up, though. Hopefully someone else will point you in the right direction. Good Luck.

 

After all you have been through SgtRon I think you've eliminated all but the PSU............Voltage checks are not the be all end all, that some would like to think, and as the PSU is an easy swap I would concur with ASUS and swap the puppy out, lot cheaper than the extra CPU price the rig has already cost you..............Please when you find the solution post back, so we can help the next poor bloke that has similar problems. Good Luck

 

I've come to the same conclusion, BC. And, as a retired techie, I recognize that voltage checks don't always tell the whole story. I'm beginning to think something made it past my surge suppression. Gonna order a new and better PSU from Newegg today and will post an update here after installation. I really appreciate all you fine troops sticking with me through this long mess!
Bless you all, and have a great Thanksgiving!

 

Well, here I sit at my now-working computer. Boy is my face red! After buying and installing a new PSU and not seeing a change in the problem, I was ready to throw in the towel. But, as I always told my students in Basic Electronics, "don't overlook the obvious" It suddenly occured to me that the stupid machine may be in hibernate mode! In that case it would be normal for the fans to come on as soon as the PSU switch was toggled. So I pressed and held the case power switch for 4 sec - - - Voila! Fans and power went off! After that I just hit the power switch and we were off and running. Although bootup is taking way too long (3 or 4 minutes) it is, as least, booting into Windows. So, the only piece of defective equipment I had in this long, sordid mess, was the mobo!
I want to thank each and every one of you who offered suggestions and comfort through my ordeal. I'm truly in your debt. The guys at MG are the greatest!

 

Two last questions, because I didn't understand everything in your last post:
If, in the end, the only defective thing was the mother board, why did you end up buying a new power supply? Could you have achieved the same thing without replacing the PSU?
And, secondly, which stupid machine? The computer itself? I didn't understand what was being blocked from running when the fans were on?
Thanks.
abri

 

Reason I replaced the PSU was because everything else had checked good and "community wisdom" here at MG indicated that it was most likely the culprit. And, in retrospect, it was unnecessary. Yes, the computer was the "stupid machine" I was referring to. (what else would you call a machine that only knows how to count 1-0-1-0-1-0, ad-infinitum?) I'm not really sure why the fans are on in it's hibernate mode, either. All I know is it would never start the POST. Holding the power switch on for 4 sec. sets everything to "off". Then, it's just a matter of turning it on as usual.
Hope this clarifies everything for you. Thanks for the reply.

 

Hi. I wonder about your power supply, too. It is possible that one of the pins in one of the connectors is not making good contact. I would check all connectors very carefully before doing anything else. Good night and good luck.