New build won't stay powered up

[HoosierDadE]

New build. When powered up for the 1st time all fans spun up for about a second then shut off. Four or five seconds later, they spin again for a second and the cycle keeps repeating. Here's the components (all new) and what I've done to troubleshoot:

ASUS P5B MB
E7200 retail
CORSAIR CMPSU-750TX PS
ASUS EAH3850/G/HTDI/512M video
CORSAIR XMS2 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 800
WD10EACS x2 HDs
Thermaltake M9 VI1000BWS case

When it wouldn't stay powered up, I then unplugged/removed everything one at a time until nothing but the MB/CPU/PS were left installed and the only case connection left was the front panel power-on button. The problem was the same at each step.

FWIW MB light is solid at all times.

I've built several PCs from scratch, but none in the last 5 years. Was "lucky" those times because everything worked.

notes:

I know I may have to play with BIOS settings for that memory before using the PC. The memory is rated for 2.1v and the MB standard is 1.8v, but Crucial says it will work and people have done it. I have the exact same memory in a Dell that also specs 1.8v and the memory has worked perfectly for over a year running at 667 instead of 800 and the Dell BIOS has no adjustability. Don't think the memory is related to the problem because its the same even without the memory installed.

I may have BIOS issues with the E7200. Wolfdales didn't exist when the board was built. Newer P5B BIOSs support it but I can't get a straight answer from ASUS whether it will boot to let me do a USB BIOS flash. Worst case, I can stick an older 775 in it to update the BIOS (don't have one at hand or I would have swapped the CPU to eliminate it as the source of the current problem). I don't think this has anything to do with the current power on problem.

The PS had an 8 pin MB connector that splits in two for MBs (like the P5B) that have a 4 pin socket. When split, you end up with two 4 pin connectors; one snaps into the other when they make up an 8 pin connector. I originally used the one that the other snapped into, but tried both after the problem and the results were the same. I don't think this has anything to do with the problem.

It seems to be down to the MB, CPU, PS or case power-on switch (very unlikely).

I'm looking for advice on things to try or ways to isolate the problem. I sure don't want to start randomly RMAing the PS, MB, CPU and case.

TIA

 

[MTDEW]

reseat the cpu and be sure the mobo isnt grounding on the case.

Ive had that happen during builds and after i removed mobo, reseated cpu and put it all back in, it usually solves that issue.
I always do both, so it could be either one.

 

[KGB]

The symptoms you described COULD be explained by a faulty power switch.
Try disconnecting it and powering up by touching a screwdriver momentarily to the MB power header pins.

Two other things: Clear the CMOS and check that you have the CPU fan plugged into the correct MB connector.

 

[HoosierDadE]

Thanks MTDEW and KGBMAN

Originally posted by: MTDEW
reseat the cpu and be sure the mobo isnt grounding on the case.

Ive had that happen during builds and after i removed mobo, reseated cpu and put it all back in, it usually solves that issue.
I always do both, so it could be either one.

I reseated the CPU. Still keeps turning on and off. While out, I carefully looked for any bent pins on the MB (although I don't know why they are called pins in a 775). All looked good.

I removed the MB from the case completely and sat it on the ant-static bag it came in on a wood counter and reattached the 24 pin ATX, the 4 pin EPSV12 and the case power switch. Still keeps turning on and off.

I saw another thread (totally different topic) that mentioned someone powered up their MB with NO CPU installed and I tried that as well. I left the CPU fan plugged in. This time the fans (CPU and PS) kept running.

So, I'm thinking that doesn't completely rule them out but it makes it less likely to be a PS or case switch problem. And makes it more likely to be a MB/CPU problem.

Originally posted by: KGBMAN
The symptoms you described COULD be explained by a faulty power switch.
Try disconnecting it and powering up by touching a screwdriver momentarily to the MB power header pins.

Two other things: Clear the CMOS and check that you have the CPU fan plugged into the correct MB connector.

I cleared the CMOS. No change.

I jumped the power switch pins with a screwdriver. No change.

Yes, the CPU fan was plugged in correctly.

----------------------------------------------

Apparently the fans powering on and off problem only happens when the CPU is plugged into the MB.

As I noted in the original post, the BIOS on the MB predates Wolfdales and the ASUS site says a fairly recent BIOS does support them. My thoughts were that the BIOS would either say "huh?" and do nothing with the Wolfsdale, or the system would run in some degraded level and let me update the BIOS (MB supports BIOS updates from a USB flash drive). ASUS still won't respond to my questions about that from well before building the PC.

I would never expect the CPU to be able to run the BIOS code and then have the BIOS decide to shut everything off and then turn everything back on again in a few seconds ad nauseum. But what do I know? LOL

Nor would I expect a power supply that didn't like what it saw to keep recycling. Or rather, I can imagine that but not have it keep the standby power to the MB going. The MB standby light stays on constantly while the other power (including the peripheral device power) turns on and off every few seconds.

Any other ideas appreciated.

BTW, whats the green way to recycle all the hair I'm pulling out. ;-)

 

[HoosierDadE]

I took a 6400 out of a Dell I have and stuck it in this build.

It fired right up. So the problem with the E7200 is definitely a combination of BIOS and/or CPU.

With the 6400 in it, I flashed the latest ASUS BIOS that says it supports the E7200 and stuck the E7200 back in.

Now I expected everything to work fine or go back to the power-on power-off cycling.

But now the fans and peripherals keep running but there are no post beeps, keyboard lights or any video.

Stuck the 6400 back in just to make sure nothing else changed and the 6400 still worked perfect. E7200 back in and nada.

It looks like the E7200 is a dud. I thought that was the least likely of any of the possible causes.

RMA time.