PC Won't POST unless you unplug it first

March 14, 2016 at 11:23:45
Specs: Windows 7
We have a Dell Precision T3600 Workstation. The PC will not power on correctly.

1) Was under Warranty, called Dell Support. PC was bought originally I Japan, so waiting for Transfer of Ownership before we can get it replaced.

2) Dell Sent first time New MOBO + Video Card + PSU. Replaced all of these, unit still wouldn't power on.

3) Dell Sent Another MOBO + Power Cord (wrong one, so couldn't replace) + CPU. PC Still wouldn't POST

4) I was getting LEDs 3+4 lit. (indicating bad memory). I removed all the memory and got LED 1 (no memory). I tried one Memory chip at a time, 3 wouldn't work at all, but one chip would work (sometimes). I was able to boot PC but only if USB Keyboard and Mouse were not plugged in when I hit the Power Button.

I tried several times, sometimes it would boot, sometimes it wouldn't. I ran Diagnostics, everything passed except the Hard Drive, said missing or incompatible. This has a Hard Drive Controller Card.

I was still able to boot into Windows 7, and I ran all the Windows Updates (took forever, had about 200 updates), updating with only 2GB of memory.

I tried several times to get this to boot up and stay running, rebooting, etc.

5) I took out the remaining chip that tested OK, and put in 4 new memory chips, so now have 32GB of Memory in the PC.

This PC seems to have a problem when it tries to go into Standby mode.

I updated the BIOS from A12 to A14 and I turned off Power Saving Mode.

One thing I notice is when I plug the power cord in, sometimes CPU Fan will run really fast when it gets power (when it does, it will boot up), othertimes it doesn't and it won't boot up. Power Button does nothing. I unplug the USB Keyboard and USB Mouse (I have also tried different Power cord and different keyboard, no difference).

I have removed the Hard Drive Controller and plugged Hard drive directly into the MOBO, no difference.

Dell is going to replace the unit, but it could take 15 days for transfer to happen then another 15 days to get the new replacement PC. We need this PC for a Lab computer. I was trying to get this running until it can get replaced.

Anyone have any other suggestions?

Oh, I have also tried different Monitors as well, I also tried removing CD Drive, Hard Drive, etc still powers on intermittently.

See More: PC Wont POST unless you unplug it first

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March 14, 2016 at 12:37:02
The speed up of the fan indicates overheating. When you changed the motherboard did you use the proper procedure for applying thermal paste to the CPU/heatsink connection?

Of course the memory modules are an issue. If not filling all memory slots you must install in the correct slots. Consult the manual on that issue.

Did you connect the auxiliary power connector to the motherboard?

You mention removing the hard drive controller. What type of hard drives are installed. The Specs have options on both the controller and the type of drives. At any rate you probably need to use the controller card.

The computer should boot to the BIOS without ANY hard drives or controller cards installed. Just can't boot into the OS.

So, I would look at the thermal paste and/or the memory has the problem with booting.

See the link below for proper paste application. Works the same for all brands of paste.


message edited by OtheHill

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March 14, 2016 at 15:46:47
It reads to me that the "speed up" of the fan is just the normal initial
speed before the motherboard takes control of it. The high speed
should normally last for just a couple of seconds.

Overheating could still be a problem, but starting with a cool system,
I can't imagine heat problems showing up until well into the POST.
If the POST begins normally but never completes, that may be it.

-- Jeff, in Minneapolis

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