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No POST, will not shutdown -- CPU or grounding?

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August 23, 2010 7:59:00 PM

This is an ongoing problem I've been having with a build. All of the fans startup when I power it up, but I get no POST, let alone a boot. However it is impossible to turn off via the power button. The reset button as no effect either. I've swapped out the PSU and got the same problems, so it can be ruled out. The motherboard gives a green led light and I previously had a foxconn motheroard in the system with the exact same sysmptoms.

I'm therefore thinking there is a problem with the CPU, or maybe a grounding issue? So far I've tried everything on the hardware troubleshooting guide on the forums, other than resetting the cmos.

Asus M4A87TD/USB3 870 Socket AM3 8 Channel Audio ATX Motherboard
AMD 955 @ 3.2 ghz
OCZ Stealth xtreme 600w PSU
Coolermaster 330 case
Seagate barracuda 7200rpm 500gb
samsung CD drive
2X 2GB of OCZ ddr3 1333

August 23, 2010 8:48:12 PM

I'm assuming you DID connect the case power and reset buttons to the motherboard?

If you had the same problem with a different motherboard then perhaps it's the CASE with the issue, perhaps the buttons aren't working...

Does it beep? Beep codes can be used to figure out what the post issue is.
Also, I'm assuming nothing shows up on screen?
Have you tried a cheap video card to see if the motherboard is just not outputing video properly? If nothing comes on the screen then it could be a video issue. Have you tried a different monitor and different monitor cable?
August 23, 2010 10:10:30 PM

Yep, all of the case cables were plugged in, including the beep code speaker. No beep codes when it powers up and no video output. The foxconn I put in previously had an integrated gpu, so that should rule out my current gpu as the cause. Yes, I've tried a different monitor, but not a different cable; I've tried HDMI so far so I'll give DVI a shot, but I don't think its gonna do much. The question still stands why I can't shut the system down or restart it via the buttons.

I have considered whether the button might be broken, but shouldn't this not be an issue if the button can power the system on? Another quick question, does it matter which of the two four pin cpu power connectors you use? I've plugged in the one labelled "1" and was just wondering whether this might be the cause of the problem, I though both four pins supplied the same power.
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a c 122 B Homebuilt system
August 24, 2010 3:53:23 AM

The POST can be successful (a single short beep) or unsuccessful (any other beep pattern). Silence indicates that it did not run.

Here's a link to a step by step building guide. Review it to make sure you didn't leave anything unconnected.
http://www.tomshardware.co.uk/forum/274745-13-step-step...

Work through our standard checklist and troubleshooting thread:
http://www.tomshardware.com/forum/261145-31-read-postin...
I mean work through, not just read over it.

Breadboard - that will eliminate any kind of case problem you might have.
http://www.tomshardware.com/forum/262730-31-breadboardi...

Breadboard with just motherboard, CPU & HSF, case speaker, and PSU. You do have a case speaker installed, right? If not, you really, really need one. If your case or motherboard didn't come with a system speaker, you can buy one here:
http://www.cwc-group.com/casp.html

You can turn on the PC by momentarily shorting the two pins that the case power switch goes to.

You should hear a series of long, single beeps indicating memory problems.
Silence indicates a problem with (in most likely order) the PSU, motherboard, or
CPU. Remember, at this time, you do not have a graphics card installed so the load on your PSU will be reduced.

If no beeps:
At this point, you can sort of check the PSU. Try to borrow a known good PSU of appropriate ratings. If you cannot do that, use a DMM to measure the voltages. Measure between the colored wires and either chassis ground or the black wires. Yellow wires should be 12 volts. Red wires: +5 volts, orange wires: +3.3 volts, blue wire : -12 volts, violet wire: 5 volts always on. Tolerances are +/- 5% except for the -12 volts which is +/- 10%.

The gray wire is really important. It should go from 0 to +5 volts when you turn the PSU on with the case switch. CPU needs this signal to boot.

You can turn on the PSU by completely disconnecting the PSU and using a paperclip or jumper wire to short the green wire to one of the neighboring black wires.
http://www.youtube.com/watch?v=5FWXgQSokF4&feature=yout...

This checks the PSU under no load conditions, so it is not completely reliable. But if
it can not pass this, it is dead. Then repeat the checks with the PSU plugged into the computer to put a load on the PSU.

If the system beeps:
If it looks like the PSU is good, install a memory stick. Boot. Beep pattern should
change to one long and several short beeps indicating a missing graphics card. Silence or long single beeps indicate a problem with the memory.

Insert the video card and connect any necessary PCIe power connectors. Boot. At this point, the system should POST successfully (a single short beep). Notice that you do not need keyboard, mouse, monitor, or drives to successfully POST.

Now start connecting the rest of the devices starting with the monitor, then keyboard and mouse, then the rest of the devices, testing after each step. It's possible that you can pass the POST with a defective video card. The POST routines can only check the video interface. It cannot check the internal parts of the video card or on-board GPU.
August 24, 2010 11:30:59 AM

This is getting weirder and weirder. I just tried the motherboard without the cpu to see if I could power it off, but it still wont respond. Mayhaps I've had the misfortune of getting and installing two dodgy power supplies in a row?
August 24, 2010 6:27:03 PM

Just got the OCZ PSU tested out at a local computer store and it appears to be fine. I guess that leaves me with possibility of a dody cpu. Does anyone know wether not having a cpu installed would prevent a hard shutdown via holding in the power button?

Thanks in advance.
August 28, 2010 11:55:51 AM

Got an update, I stuck my firends's phenom x2 555 in my system I got the exact same symptoms again?

I've tried a different monitor and a different wall socket without any success. The only things that haven't been swapped out are the ram and case. Since taking the ram out has no effect whatsover, is it possible that the case is the issue?

I read somewhere that the case powers the motherboard on by sending a burst of voltage, what if it is not a burst? I.e. equivalent to turning on the computer but continuing to press the power button?

Otherwise I'm pretty much out of ideas and fear that I'm gonna have to do some breadboarding.
August 29, 2010 11:36:29 PM

It seems I've solved my problem, it was the case all along... I curse you cooler master.

Anyhow, the case actually has a speaker (should have made this clear earlier), but I suspected that it wasn't working. Since it would take so long to get one in ordered in and I went up to a local car boot this morning and brought a whole computer system for £5 (pentium 1, yay), so that I could hook up its speaker for breadboarding.

First off I breadboarded the old foxconn board with my friend's x2 555, and to my suprise, it booted to bios. Even more suprising was that I eventually got the asus to boot, the beeping was music to my ears. As such I think that there may have been some sort of grounding problem with the case, mayhaps somewhere in the power switch cable? Might have been the standoffs, but odd how they caused two motherboards to ground (I'm still convinced the foxconn had the same problem, only that upon solving it I would probably have got cpu power issues).

Going to get a RMA for the case and will likely end up replacing it with an antec 300. One last question guys, if the grounding problem persists with a new case, would rubber washers on the standoffs cause any issues?

Thanks to all those who contributed to the thread; it Tom's Hardware seems to have a great community.
!