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PSU too weak, or faulty? Or something else?

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November 23, 2006 8:52:32 PM

Ok, I'm looking for any advice here on a problem with my new PC parts.

CPU: Intel Core 2 Duo E6400 (stock HSF)
Mboard: ASUS P5B
PSU: Antec NeoHe 430W
Memory: 1Gb DDR2 PC5400 Corsair Value Select
Graphics: XFX GeForce 7900GS
HD: Maxtor DiamondMax 200Gb SATA

I installed them all and hit the power button to see the CPU fan spin for a second before stopping. Then 4 seconds later it span again for a second before stopping. This continues, all the while the power light illuminates as the thing tries to power up.

I've reset the CMOS, reseated RAM etc etc and now believe the PSU to be either too weak or faulty. After unplugging everything and simply leaving cpu, fan and memory it starts up fine with the CPU fan spinning fine. With the Graphics card plugged in I can see the fan spinning but I'm not getting any display. The moment I plug in the power for the HD (not even connected to the Mobo) the thing drops back into the original state.

To me this suggests that the PSU is too weak but my calculations on the PSU calulator (linked from this forum) fall well within 430W. I appreciate that the 12v rail is the important one but I've no idea how to determine the limits of that and I'd assume this Antec supply would be sufficient. So is this too weak? Faulty? Or could it be something else?

Any help would be appreciated and thanks in advance.

More about : psu weak faulty

November 23, 2006 11:19:55 PM

Quote:
After unplugging everything and simply leaving cpu, fan and memory it starts up fine with the CPU fan spinning fine. With the Graphics card plugged in I can see the fan spinning but I'm not getting any display. The moment I plug in the power for the HD (not even connected to the Mobo) the thing drops back into the original state.


Try the cd/dvd drive and a bootable CD like ultimate boot cd or knoppix (maybe the hdd is bad?). If nothing I would take it a step further, try it with the speaker plugged in and try it w/o the video you should get the "no / bad video" beeps. Same w/ memory you should get the "no / bad memory" beeps. Then try it with the memory and w/o the CPU you should get "no cpu" beeps. Heck I recall times when similiar things happen I remove everything from the case and put it on the bench it works fine, maybe it is grounding out in the case somewhere?
November 23, 2006 11:30:01 PM

Does sound like a PSU problem, only way to know is to try another or get a psu tester.
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November 24, 2006 12:23:56 AM

Is the CPU power pluged in?
November 24, 2006 7:17:02 AM

Quote:
Try the cd/dvd drive and a bootable CD like ultimate boot cd or knoppix (maybe the hdd is bad?). If nothing I would take it a step further, try it with the speaker plugged in and try it w/o the video you should get the "no / bad video" beeps. Same w/ memory you should get the "no / bad memory" beeps. Then try it with the memory and w/o the CPU you should get "no cpu" beeps. Heck I recall times when similiar things happen I remove everything from the case and put it on the bench it works fine, maybe it is grounding out in the case somewhere?


Well, if I plug in the DRW/DVD combo drive alone, that seems to power up fine but with no display there's no much I can do with a bootable CD (which I don't have anyway). I'll try running it out of the case this weekend and try to eliminate parts. I've not had any Post messages from the thing but when it does the spin up/spin down it's never going to reach post anyway.


Quote:
Does sound like a PSU problem, only way to know is to try another or get a psu tester.

I'll try and source another PSU to try then.


Quote:
Is the CPU power pluged in?

Yep, both the 4-pin and the 24-pin are connected


Thanks for the help so far guys, I'll try get through some of those suggestions this weekend. However nobodies commented on the actual strength, or quality, of the Power Supply I've got there. Things have moved on a bit since my last build and PSU's are far more important than they used to be. Have I simply understimated my consumption requirements with that PSU?
November 24, 2006 10:57:12 AM

which P5B do you have?
November 24, 2006 3:34:38 PM

Antec is a mid level psu maker, not as good as some and not as bad as others.

430w should be sufficient for your needs but that's only if it's actually putting out 430w.
November 24, 2006 9:21:33 PM

Ok I think I've come to a fairly concrete conclusion that the PSU is faulty. Worse still, I think I've been a little stupid. Having taken all the components out of the case and laid it out 'alien autopsy' style on the desk even the simple combination of CPU and RAM was getting the aforementined lazy spinning of the fans.

After just about giving up I checked one obvious clue, the fan inside the PSU itself. Sure enough, the PSU fan is spinning up and dropping out just like the rest and must be the root cause. Back to the shop for that one I think.

A big Thankyou for the responses folks. With any luck I can get a replacement and get this thing doing what it was supposed to some time soon.
!