PC will not boot

[bodomprophet]

Hello. I've had this problem for a few months now and I'm at my wits end on how to solve it.

I recently put together a new PC a few months ago. The problem is that the PC will not boot at certain times. If I power my PC off, I will not be able to start it again for several days. I've come to believe it may be temperature related, as it only seems to boot after sitting with the power cable unplugged overnight. Also, if my computer room is above 72°F it will not boot. This may be a coincidence.

When I press the power button, all the LED's light and the fans spin for a fraction of a second and then go dead. If I press the power button again, nothing happens. In order to show some activity, I need to either hold the power button in for 7 seconds, release, and then press the button again.... or remove power from the PSU for 7 seconds. Eventually... on some occasions the PC will boot and I do not turn it off again because of this problem.

I first thought this was a motherboard problem, so I RMA'd the motherboard. I still have the same problem. I tested the PSU by shorting the green wire with a ground wire... the PSU powers fine in this fashion. I tried using a different power switch, and the same problem occurs. I have no idea what to do. I estimate whatever is broken will cost at least $200 to fix, so I want to be sure I'm replacing the correct component. Can someone please help me? My system specs are as follows:

Case: My case is highly modified, to support a water cooled system. I used a dremel tool and an electric drill to modify the case. I vacuumed all metal shavings from the case before installing the components. (Since this is a water cooled system, I also tried installing the CPU fan, but the PC still will not boot)

CPU: P4 LGA775 3.4GHz HT (prescott core)
RAM: 1gb Corsair DDR2-667 XMS2 Pro (in dual-channel config)
Mobo: Asus P5AD2-E Premium
HDD: Silicon Image RAID 0 w/ (2) Maxtor plus9 120gb
Video: MSI (ATI)Radeon X850XT PCI Express 256MB
PSU: Thermaltake Purepower 680 APD
Removable storage: 1 generic 1.4 floppy, and 1 Liteon DVD/CD RW combo.

That's about all internal devices. Can someone please help me on this situation? I would be most grateful! Thank you.

 

[BadBigBen]

Hola,

have you actually physically tried another PSU (as certain types of PSU have a thermal sensor that cuts the PSU output and/or certain Voltage rails, in order for it to cool down)...



Ben

If it works don't fix it! If it doesn't use a sledgehammer...

 

[Wishdiak]

When I press the power button, all the LED's light and the fans spin for a fraction of a second and then go dead.

That certainly sounds like a bad PSU to me.

Wishdiak
A+, Network+, Security+, MCSA: Security 2003

http://www.wishdiak.com

 

[rvnguy]

bodomprophet,

I had a similar sounding situation with an older PIII on a HP MOBO that I salvaged. I had to install a CPU heatsink & fan(aas the HP sys used their own cooling setup & this was transplanted into an ATX case).

Power up.. runs for several seconds and the HS fan stops.. boot stops.. and video output stops. Looks like it is off but the protection in the CPU has shut it down. I needed to depress the power button for about 4 seconds and it then actually powered down. CPU was over heating and was interrupting the process. I had a problem getting the HS retaining setup to allow a square install.

The P4 has the similar circuitry. Check your water block install and insure that there is adequate, but not too much thermal interface compound. Check your retainning system for correct installation (to allow an even and square application of pressure) when water block is installed.

This might be a problem like I had and then again maybe not. Easy enough to try and check though.

rvnguy

"I know everything..I just can't remember it all

 

[DrAlbany]

HI..,

Make sure you don't have too many brass upstands... Count the number of screws on the mobo side, then have a look on the back plate and make sure there are the same amount of threads sticking through.... it's so easy to get an extra one shorting the mobo out.

As previously mentioned check to make sure the heatsink on the CPU is seated properly.

Also disconnect any leads and plugin cards accept VGA so that the only thing connected to the PSU is the mobo, heatsink & fan and VGA (if not onboard)

I would then be tempted to take the motherboard out and sit it on a piece of card (or other insulation) and test the mobo outside of the case.

It does sound more like a mobo / PSU issue.

Hope this helps.

 

[garebo]

You could try using just one stick of ram at a time.


Good advice + great people = tek-tips

 

[firewolfrl]

Hmmm! do you have the option of trying a different CPU?
Does the system reset and you loose your previous settings?
CPU incompatability can be the culpret...the board may work with your CPU and that type of CPU but it just may dislike the CPU you are using.
see if you can turn off the CPU protection?
PSU may cause the issue.....but, I am not so sure it is the issue

 

[bodomprophet]

Thanks for all the responses. Unfortunately, I do not have access to another LGA775 CPU, or a PSU with a 24 pin ATX connector; both of which the motherboard requires.

I will have to investigate some ideas that were presented here . Hopefully I can fix this problem without having to RMA or purchase any replacement components.

I thought it was a PSU problem at first as well, until I tested it by shorting the green wire. That's when I decided to RMA my mobo. If none of the suggestions posted here works, I think I'll have to buy another PSU.

Thanks again for all the replies, and if anyone else has any other thoughts on my situation I would be more than happy to read them. Thank you!

 

[rvnguy]

bodomprophet,

In your orig post you stated

"on some occasions the PC will boot and I do not turn it off again because of this problem."

When this happens..does it run reliably as long as you do not turn it off??? If so can you reboot/restart without a problem?
I realize that if you completly power down you have a problem.

Is you cooler of the "peltier" type if so you should be able to start just the cooler...wait until the cooler temp is around "0"C and then boot the system. "Peltier" systems need to pre-cool as they initially are not efficient enough to cool right off. Just a thought.

rvnguy


"I know everything..I just can't remember it all

 

[bodomprophet]

That's correct. I can reboot with no abnormalities. It's only when I power down the PC I run into problems (or a power-failure and things of that nature). There is no peltier in my machine.

I do not believe this is a CPU overheating issue, as the BIOS temp readings are good and I also installed an independent thermal diode, which only read 2 degrees cooler than the BIOS. The temps are pretty consistent with 10° above ambient idle and +15° w/ load.

 

[G0AOZ]

What you have told us so far suggests to me it's the PSU. A power supply that has already been successfully started up and is running, is under nothing like the same load on a reboot as it is when it's being switched on from zero volts.

You said "I tested the PSU by shorting the green wire with a ground wire... the PSU powers fine in this fashion.".

Did you carry out this test with the 24-pin power plug attached to the motherboard, or disconnected? Was the PSU also powering the HDD, DVD and Floppy drives at this point?

ROGER - G0AOZ.

 

[garebo]

In order to properly test the power supply you have to test each line that gives different voltages. Just shorting it out is only one small test, not even close to telling you if the power supply is good or not.
You can google a free tutorial on how to troubleshoot a power supply, or you can get a good one free at techrepublic. You do need to sign up but its a professional site anyway. Plus, you need a multimeter to do the job, a digital is preferred over analog but i am told either will do.


Good advice + great people = tek-tips

 

[NickS]

I am having the exact same problem. I jusr transfered the guts of my perfectly working system to another case with the exception of a few different components. The system will power up for a second, for 15-30 seconds or will boot perfectly. Sadly it booted perfectly only about three times (out of approx 50 attempts). Once booted it will work perfectly, so this removes the possiblility of CPU overheating. I am almost certain the board is being shorted by something underneath.
I will be removing the board this evening and boot it out of the case.

Will keep you posted
Nick

 

[garebo]

I stand pat with what i said on the power supply above needing to be tested properly. Just shorting the green wire
is only one of many tests needed to make sure the power supply is good. I mentioned that you can google the info you need or go to techrepublic.com and get it there.

I would also suggest you take the motherboard out of the case and test it on your tabletop.
I would also remove any and all peripherals that are not absolutely needed to boot up. If all is well then add back more parts, one at a time. In this case, you would want to turn the pc off and boot cold each time you add another part.
I am not totally convinced its the power supply but it certainly, at this point, looks like a power supply issue.
Further testing and such will show you what the problem is.


Good advice + great people = tek-tips

 

[NickS]

I also forgot to mention that i did swap the power supply and still had the same issue

 

[garebo]

Well, that would change things, lol.
Best to take it out of the case and test it with minumum system hooked up.


Good advice + great people = tek-tips

 

[NorthsideIT]

Hmmmmmm sounds like faulty pots to me