Computer won't boot

[Lenton]

I'm hoping you guys can help me with this, because I'm all out of ideas.

My problem is that my fairly new computer won't boot at all. I built it around 30 days ago, and I had this same problem when I initially built it. At the time, I unhooked everything, reattached it all, and it worked. I've been using and gaming on the computer for the last month. Heck, I was on it this morning. So I thought it was fixed.

Fast forward to a couple of hours ago. I decided replace the stock thermal grease with AS 5, and when I tried to boot, I got nothing, just like when I first built the computer. The CPU and case fans spin ~1 cm or so, but then they stop. The difference today is, I've taken everything out and put it all back together, and it still isn't working.

I just tried a different power supply, and the same thing happens.

Here's my setup:
Core 2 Duo E4500
Gigabyte P35 DS3L
Western Digital SATA HD 160 GB
Corsair 450VX
PNY 8800 GT
GSkill 4GB DDR2 800 RAM (2x2 GB)
ASUS SATA DVD Drive
Windows Vista Home Premium 64 bit
Coolermaster 690 case

Again, any help is appreciated.

 

[Harvey]

It sounds like either your power supply is failing, or something in your setup is shorting to ground. Try removing all of your plug in cards and peripherals, including drives, except your vid card. Then, remove and reseat your vid card and try booting.

If that doesn't fix it, try carefully removing the screws holding the motherboard and sliding an insulator, such as a piece of cardboard, under it.

If the problem persists, try another power supply.

Hope that helps.

 

[Lenton]

Well, I tried a different power supply, and the same issue happened.

I'll try sliding something under my MB.

 

[Lenton]

Same issue after trying a different PS and after unscrewing my MB and sliding cardboard under it.

What else could it be?

 

[Lenton]

I'm thinking the extra PS I tested the computer with just isn't sufficient to power the system. First, it only has a 20 pin connector (my mobo is 24); and second, it is a 430 watt Raidmax...

I also found something else. My Corsair 450 VX has a missing wire on the 24 pin connector. It corresponds to the -5V rail on the motherboard. Would this cause my system not to boot?

 

[robisbell]

when you replace the thermal paste, did you thoroughly clean off the old from the cpu and heatsink before applying the AS5?

 

[Lenton]

Yeah, with high purity isopropyl alcohol.

 

[bwatson283]

sounds like a CPU issue or a PSU to me.

 

[Lenton]

Alright, I just put in a new Earthwatts 430, and the same thing happens. So, it can't be the PSU.

What else can I test?

 

[Slammy1]

If the computer won't even post, you have a very specific issue. Typically, it's PSU related in my experience but you may have damaged the CPU while replacing the paste (which could also cause the behavior you're observing). Make sure your internal speakers are attached as that will give you the post code, reset your CMOS (remove the battery for a few minutes while the PSU is off or unplugged), and if it still doesn't work go down the list.

http://www.computerhope.com/issues/ch000607.htm

 

[Lenton]

Well, I just took the computer to a repair shop, and had the tech look at it in front of me. He put a different PSU and different Core 2 Duo CPU in, and the same problem still occurred. He told me that he's pretty sure it's a MB issue, and I'm starting to lean that way.

I wish my case had internal speakers, but it doesn't. I did reset the CMOS already.

Any other ideas before I RMA my board?

 

[jackschmittusa]

You don't need the -5v. Many psus don't have it wired.

The short fan spin is often a sign of an electrical short. The psu kicks out as soon as it detects it. Any bent pins on any mb connectors? Proper placement of stand-offs for the mb? All of the i/o plate fingers on the outside of the connectors?

Take the mb out of the case and inspect it. Test it on the bench. It sounds as if the problem is intermittent and is affected by physically stressing the mb (seating cards, hsf, etc.).

 

[Lenton]

Alright, the bench test worked. It fired up promptly. I guess that means it was a short, but how would I go about finding it? (forgive me if I sound like a noob)

 

[jackschmittusa]

Common short problems: having a stand-off on the mb tray where there is no mounting hole on the mb, small fingers on i/o plate misaligned during installation of the mb so that they go inside of a connector instead of on the outside, mis-wiring the front usb ports.

 

[Lenton]

It's up and running great now. Thanks for your help everyone.

 

[robisbell]

what was causing the short?

 

[Lenton]

I'm not sure; I wasn't able to isolate it. So I just put everything back in and it's working great.