Blinking PSU, no power to CPU.

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Moocat

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Sep 11, 2005
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Hey folks. My mother's old Windows system has started acting like Windows machines do after a few years, so I decided I'd build her a new machine that dual-boots Windows and openSUSE Linux. For this new machine, I used some of the spare parts that I had lying around my apartment, and some other spare parts from my little sister's computer she that she used in college then gave to me for scrap. Here are the components I used and where they came from.

CPU (used, formerly mine): Pentium 4 Prescott 3.0GHz HT.
MB (used, formerly mine): ASUS P5N32-SLI Premium.
RAM (used, formerly mine): 2x Corsair XMS2 512MB sticks. This RAM and the above two parts were together in my old system before I scrapped it.
CPU HSF (new): Masscool xxx. Don't have specific information on-hand. Will provide if requested. I just have to dig for it. Used Arctic Silver 5 for thermal compound.
PSU (new): Rosewill RP550-2 550W. Bought on Newegg, had problems (described below), RMA'd it, the 2nd one had same problems, so it's probably not the PSU.
Video Card (new): ASUS EN7200GS. No problems as far as I know. The following problem occurs with or without video card seated.
HDD (new): WD Caviar 300GB SATAII No problems afaik.

*************************************************

Alright, on to the problem. The above system uses the same case, CPU, MB, and RAM as one of my old systems. HSF, Video card, PSU are all new.

I put all the pieces together, as usual, and plugged everything in. The hard drive is still blank as I need to get the machine running first, obviously. The problem is that when I plug in the EAX12V 8-pin connector in to the CPU power connector on the motherboard, the PSU's LED light will flash on and off, make a clicking noise, PSU fan starts and stops at regular intervals. Sizzling sound can be heard from CPU area. I quickly powered down the machine, unplugged it, and thought about some steps I could take to trouble shoot. First thing I did was unplug the power to the CPU (EAX12V 8-pin connector). Plugged the PSU back in to the wall, powered on the machine, and all the fans spun up properly, and the PSU operated just fine. I phoned Rosewill. They gave me a generic test to ensure the PSU is working properly (jump main motherboard connector with paperclip). The PSU passed the test. I RMA'd the PSU anyway... only to have the same problem with the replacement.

I placed an order for some Arctic Silver 5 to reapply the thermal grease to the CPU. I did so, and it turns out that this is not the problem either. The clicking, sizzling, and flashing continues.

So now, I think I am in a position where I will have to either buy a new motherboard or CPU or both. Remember that I've already RMA'd my PSU and confirmed it is in working order with the manufacturer twice. Basically, what I need to know is :

What in the world is causing this problem? CPU? Motherboard? Both? Something else entirely?
In the past I've always built my system from a majority of new parts, and am not used to diagnosing problems like this. Any help would be immensely appreciated.

Thanks!
 
Joined
Sep 1, 2004
Messages
1,756
It sounds like you've either got a short somewhere (e.g. a screw jammed underneath the motherboard, or a broken socket) or you've killed the motherboard.
 

Moocat

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Joined
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112
OK. What leads you to believe this? Is this a common symptom? I should test the system on bench I suppose. It is possible that there is a short as the motherboard was left sitting around for about a year in the top of my closet. Any techniques for finding and fixing the problem?

Thanks!
 
Joined
May 3, 2006
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Try outside of the case with 1 ram stick, psu, cpu, video card and short the power jumper with a screwdriver to start. See if it will post that way.
 

Moocat

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Sep 11, 2005
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112
I need to get an open workbench. What sort of surfaces would be good for this? Thanks again!
 
Joined
Aug 2, 2007
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777
Wood is best for your bench. Still, take proper precautions against ESD.

Sizzling is never a good sound. I'm not a Rosewill fan. Definitely test PSU on a known good, compatible motherboard.

Remember the parts upon which one should NEVER go cheap or shallow: PSU, memory, motherboard (at the very least, those three).

Even if you RMA it and get a new one, there is NO guarantee in the world of precision electronics that something didn't go wrong in transit. Remember: More than likely, that PSU followed the same path as the former.
 
Joined
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11,670
I would suspect one of three things that may be the problem.

#1-Take a bright light and acerfully examine the motherboard capacitors for any with swollen or bulging tops. Also, look for any that may be leaking a brownish looking fluid. If you find these symptoms then the problem is bad capacitors.

Attached is a link showing what you should be looking for.

http://www.badcaps.net/ident/

#2-Processor. Have you checked the Asus site to make certain that the particular processor you are using is compatible with the board?

#3-The power supply. Jumping the PS ON wire (green wire) to ground only tells you that the PSU is starting up, it tells you nothing about output. Have you tested the PSU with a power supply tester?

It is definitely possible to get two defective products of the same make and model from a re-seller. The reason being, re-sellers generally get components in carton quanities. In some instances the re-seller may get in a carton of components that all have the same defect.

A few years ago, I purchased a board from a re-seller, and when the board arrived I found it to be defective. I RMA'd to the re-seller for another board of the same make and model. The 2nd board I got was also defective, which I returned for credit. I then ordered the same make and model board from another re-seller, and the board was good, no problems. The entire carton of that board from the first re-seller all had a same defect. By getting the same make and model board from a different "batch" solved the problem.
 

Moocat

Thread Starter
Joined
Sep 11, 2005
Messages
112
1: Doesn't look like there are any bad capacitors. It was one of the things I already checked over, but after checking again I still haven't seen any.
2: Processor is compatible. Used it with this mobo in an old machine.
3: I do not have a tester :( I can try the machine with my psu in my other machine, but that can't happen for a few months (my machine is 300 miles away).

Thanks!
 
Joined
Aug 2, 2007
Messages
777
Alternatively, see if you can get a good PSU to work on that motherboard.

I had one client whose computer was fried as far as the motherboard and PSU were concerned. When I plugged the suspect PSU into a known good motherboard the PSU sizzled, smoked, and I turned it off immediately! As for the motherboard, it wouldn't start no matter what PSU I used. The cause (which came out eventually): Their house was near power lines that had been struck by lightening. And they had no surge protector.

Hope better for your system. :)
 
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