Computer won't Boot, Blank screen

[damenka]

Hey!

A little more than a year ago I built a decent computer (with your help. thanks!).
A couple of months later the computer mysteriously stopped working and the only sign of life was a lamp glowing on the motherboard. The fans also spun for less then a split second when trying to power the computer for the first time after plugging in the power cable. I figured it was either the motherboard or the CPU, but I didn't have the time or the money to look into it back then.

Now, more than 6 months later I've found the time and some money to try and take care of it. Yesterday I tested some parts and bought a new motherboard. After installing the motherboard, the computer will turn on, but it will turn off after a few seconds then turn back on and remain that way until i turn it off manually. During that time my screen remains black. I've tested all components except the CPU now so I'll probably have to buy a new one. But I have a few questions before I do that.

First off here is my Specs:
1x MSI Twin Frozr II GTX 580
1x Corsair TX750
1x Intel i5 2500k with stock fan
2x Gskill Ripjaws X 4gb
1x Samsung SpinPoint F3 HD103SJ 32MB 1TB
1x NZXT Hades case
the new motherboard I bought was: ASUS P8Z77 LK
and the old one was: Asus P8P67 Pro B3

Do you think there is anything else that might be causing my problems? I've tested the ram, Graphics card, Psu and Hdd on another machine and they all work. I've tried putting the ram in different slots with the same result as earlier. I've tried resetting the cmos following instructions in the motherboard manual.

If you think the cpu is causing this, would you mind helping me chose what to buy?
I've been thinking about buying an Intel Core i5 3450 3,1Ghz Socket 1155, it seems alright and not too expensive. It's not unlocked but I don't think I have the guts to mess around with this computer anymore anyway.

Thanks for your help!

Edit: I forgot to mention that I didn't find any chipped pins while studying the CPU. I also can't seem to find the speaker cable (the one you plug into your motherboard) so my computer is mute and probably can't beep.

 

[sPlAtOiD]

Have you tried to setup the system out of the tower. You could be getting a ground out. Just find a box to set the motherboard on and put on your video card ram CPU and power it up.
You will need to cross the two power pins to fire it up.Try with just one ram stick if you have two then try the other. after you try that and if you still have no luck. take off your CPU fan and put your finger against the CPU chip and fire it up for just a few seconds to see if the CPU starts to heat yo. If it does you still have voltage going to the CPU and it no doubt is still good.

 

[damenka]

I'm gonna try this and get back to you. If it is the case that is causing a ground out (I suspect that is a synonym to short out?), what can I do to resolve the problem? Buy a new case? Fix the case?

Thanks for your help!

 

[sPlAtOiD]

Well first see if that is the problem. If so you just have to do the process of elimination. I had a computer doing this on a new build and as soon as I took the screws out and would lift one corner it would boot and run. I found the back plate for the CPU was touching the case. I just took a grinder and made a bigger whole in the rear plate of the tower so the plate quit hitting. It could be one of the screws. It may not be the problem but its a good starting place.

 

[damenka]

Ok, so I tested it out and still have the same problem as before. Haven't tried running the cpu without the fan yet, if there is any risk of damaging the motherboard I would like to avoid it. I did find that the fan was seated slightly deeper on one side of the cpu, maybe I was careless while installing it.

 

[sPlAtOiD]

If you do the test with the cpu off you only need to run it for a few seconds it only takes that long to see if it is warming up. Just turn it off as soon as you feel heat.