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Bad motherboard or PSU? Won't POST

Last response: in Motherboards
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September 28, 2011 4:22:08 AM

One morning, my homebuilt pc was working fine. When I tried to resume from hibernation that afternoon the power came on for a couple of seconds and then shut down. This happened a few more times, though in hindsight I probably shouldn't have kept pushing the power button. :(  Ever since then, when I push the power button the power appeared to stay on with all the fans spinning (case, cpu, mobo, psu, video), but there was no POST on the monitor. Also, no power to the keyboard or mouse, but the external hard drive light came on for only a second. The power and hard drive LED's stayed lit constantly. The only way to shut it down was to hold the power button for about 10 seconds.

The only thing that I did prior to this disaster - and I can't believe that this is the cause - is I updated eBay TurboLister, but didn't restart the pc to complete the update.

Here's what I've done so far to narrow down the culprit. After each of these steps, there was no change.
1. Changed the power cord and plugged it in a different slot.
2. Checked the UPS. No problem lights and the printer and other peripherals are working fine.
3. Changed the video card to an older one that worked last time I remember, albeit a long time ago. After that showed no results, re-installed the current video card.
4. Unplugged the hard drives, optical drives, and all the external cables.
5. Changed the CPU with an older Athlon 64 3000+ CPU. I didn't re-attach the HSF at first because I intended to turn the pc on for a couple of seconds. After that showed no results, re-inserted the current CPU and re-attached the HSF (after cleaning off the old thermal compound and applying new compound).
6. Removed all 4 RAM DIMM's and re-inserted only one in the first slot closest to the CPU. I went through each one and also tried plugging them into different sockets.
7. Removed the video card, RAM, and unplugged all cables except for the frontside case connections (power switch, LED, speaker, etc). No beeping at all.
8. Changed the PSU with an older Antec 380 watt PSU. It had an ATX 20-pin motherboard power connector while the board has a 24-pin slot. I read that that's okay. Also plugged in the 4-pin ATX +12V cable. Still no beeping. Just fans spinning.
9. Removed the motherboard from the case and placed it on a cardboard box. Disconnected all case connections except for the speaker. Used a screwdriver to short the power pins to turn on. Tested this way for both PSU's.

EDIT: 10. Moved the CMOS jumper to clear it for more than 5 seconds. Replaced the C2032 battery with a new one.

So I'm thinking that it has to be the motherboard, right? Is there anything else I can do to be sure? Appreciate any help you can offer.
September 28, 2011 4:52:01 AM

Have you tried to clear the CMOS yet? This usually can be done via shorting the CMOS jumpers on the motherboard or removing the battery (also found on the motherboard). Higher end motherboards will usually have a button for resetting so use that if your board has one.
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a b V Motherboard
September 28, 2011 6:04:32 AM

Clear CMOS and try starting up without anything attached (no RAM, no HDD) and try clearing the CMOS some more.

Then try it with rotating the ram sticks through the slots again.
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September 28, 2011 2:17:31 PM

Thanks for the replies. I forgot to mention that I did clear the CMOS by moving the jumper and also replaced the battery. I edited my post to include these actions.

delauder, I will try your suggestion about the RAM, but I don't see how that would help seeing that I'm not getting any beeps when there's no RAM at all. BTW, does it matter which way the case speaker is inserted in the pins?
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September 28, 2011 2:20:47 PM

I had similar issue before, it was the PSU -- I don't really agree with the 20 pin connector into the 24 pin,, see if you can borrow a good one from someone else.

if that fails,,, it is your MB
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a b V Motherboard
September 28, 2011 10:48:54 PM

If there's no beeps on no RAM, cycling it through the slots won't help.
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September 30, 2011 5:51:50 PM

Unfortunately, I don't have access to another 24 pin PSU. I'm thinking either take my PSU to local computer shop to have tested or use a multimeter and test it myself, though I've read that results can be inconclusive. Thoughts?
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September 30, 2011 8:49:10 PM

yes, it can be inconclusive as you may get voltage, but it still may not be giving enough amps.
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October 2, 2011 3:44:53 AM

I think I just found a swollen capacitor on the motherboard. It was hard to notice until I used a magnifying glass (!) - the top was slightly bulging, but no leaks. Does this take the PSU off the hook or is it still a possible cause?
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October 3, 2011 1:25:00 PM

i would say it is your motherboard --- i neglected some of my own advice to visually check all the capacitors on the board
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October 3, 2011 8:53:34 PM

Thanks, I'm feeling a little better about my PSU. I just want to make sure I don't end up frying a new motherboard, etc. Guess it's time to upgrade! There is one thing that's nagging me - sometimes I would hear a slight buzzing coming from the PC (back when it was alive). I couldn't really tell if it was coming from the mobo or the PSU. It happened on certain websites when I scrolled the page. Any idea what that was?
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Best solution

a b V Motherboard
October 4, 2011 1:08:26 AM

Yes, sounds like the motherboard. Since you changed out most of the other components and there was no change in anything that usually leaves the mobo. As for the buzzing??? I have read and in-depth review that says, (and I'm paraphrasing), the chokes, or shiny blue/gray cubes (inductors). reach their rated current and become saturated, or full, and you start to store the excess rated energy or excess saturation current in the air instead of the inductor's core. Once you reach and exceed saturation current, the inductor is saturated with magnetic flux, it loses it's inductance and stops operating like an inductor, this poses a problem as it produces electrical noise and can damage other components - mainly the MOSFETs because the current shoots up as the inductance is lost. I think you need to have an electrical degree to know exactly what is going on like this guy that did the review does but I dumbed it down to where I have an idea of what is going on.
Of course I have seen other posts here on tom's that all they had to do was change out the current power supply with one from a different company - same power rating and all so some times it's just a compatibility issue. But it sounds like that might have been the swelling you saw in some of your capacitors. Don't know what web pages might have been viewing and scrolling through that might have caused the buzzing, might be big brother watching you lol. Hope this helps
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October 4, 2011 7:39:28 PM

Thank you, Sutek. I always had a suspicion that the Corsair VX450W and the Chaintech VNF4 Ultra had some compatibility issue, but it worked for as long as it did.

I'm looking into replacing the mobo, cpu, and memory. I'm keeping my XFX GeForce 9600GT graphics card and the PSU. Haven't been keeping up for a while and I'm astounded at all the choices! Needless to say, money is a paramount concern. I'm looking at getting an AM3 socket motherboard and AMD's Athlon II x2 250 CPU. Is that a good budget choice with a decent upgrade path? Which motherboard would you guys recommend I buy? Any favorite brands? What about chipset? I have no idea how to pick one!

I use my desktop for browsing, moderate gaming (C&C3, Silent Hunter 4, Company of Heroes), music, and videos. I've never overclocked, but I'm open to playing with it. I prefer my system to be as quiet as possible.

I welcome your advice. :) 

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October 4, 2011 7:50:15 PM

you may want to start a new thread for that.

if you just want a nice low end system for now a x2 250 with a 785G AM3 chipset is a good base point to be paired with your 9600GT, I like the Asus boards, have large heatsinks

it may be tough to find a good 785 nowadays, so you may want a 760 or 880,, you won't need to spend alot
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a b V Motherboard
October 4, 2011 8:18:41 PM

Intel Pentium G620 Sandy Bridge 2.6GHz - - - - - - - - - - - - - - - - - - -- - - - - - - - - - - - - - - - - 77
ASUS P8H61-M LE/CSM (REV 3.0) LGA 1155- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 70
CORSAIR Vengeance 8GB (2 x 4GB) 240-Pin DDR3- - -- - - - - - - - - - - - - - - - - - - - - - - - - - - - 60
------------------------------------------------------------------------------------------------------------$207
New tech, ready for upgrade to a sandybridge i7 2600 for when you got some cash, video is
part of the package and probably better than your 9800GT, but you can compare and see which one you like.
And look at the memory !!! LOOKS LIKE YOU


AMD's Athlon II x2 250 CPU- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 70
GIGABYTE GA-880GA-UD3H AM3 AMD 880G HDMI SATA 6Gb/s USB 3.0 ATX AMD Motherboard- - 100
------------------------------------------------------------------------------------------------------------$170
You can probably get different mobo a little cheaper but for ~ $40 more why not get the new stuff??
Upgradeable???
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October 4, 2011 9:19:20 PM

^^^is why i recommend a new thread :) 
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October 5, 2011 3:18:12 PM

Thanks for the advice, guys. I really appreciate it. I'll start a new thread to keep it proper. ;) 
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October 9, 2011 12:41:07 AM

Best answer selected by Kimikaze.
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