Hey all,

tl;dr - As soon as power cord is connected to computer and the PSU switch is flicked the computer will start turninig itself off and on. No response from the monitor, even when the off/on cycle is stopped.

What is this usually a symptom of? Where should i start in terms of diagnostics.

I know failure to boot seems to be the topic of a couple of other threads but none are quite like my situation.

This is my second time building a computer for myself.

Case: Antec 200
Mobo: Intel DP55SB
CPU: Intel i5 650
RAM: 4 Gb (2x2gb) Patriot @ 1333 Mhz DDR3
GPU: PowerColor Radeon 5770 - ati
PSU: Antec TP 750w

Okay, my first issue is whenever i powered on the computer, even without parts such as GPU, HDD, DVD drive it would repetitively turn it self off and on. At first i just dismissed this as one of the mootherboards quirks seeing as no Drives were connected and there was nothing to boot. (i sort of knew there was something wrong but i didn't want to face it, probably). If i held down the case power button while it was /on/ and turned it off like that, it would cease turning itself off and on.

Moving on, once i finished getting everything connected and i finally closed the case, and plugged everything in. I turned it on to find no response from the monitor. The monitor still behaved like it was connected to a computer (It didn't tell me to check signal etc).
Everything else worked however, the HDD was spining and did it's thing, all the fans were whirling and the DVD drive was attending to a DVD in its bay.

I get no beeping from anything, however there are a few lights on the motherboard turn on when power is on. One blue light often flashes slowly.

I checked my GPU first with a spare, no luck. It wasn't my Graphics card.
I have taken out one of my RAm sticks and relocated the other, still no luck (could it still be ram?)
I did usual fiddling around, no luck.

I'm starting to feel like it could be the motherboad.

All the power connected to the motherboard are connected (two) could i be using the wrong one? They fit snuggly so i doubt that.

There weren't many issues i faced while building. One thing i can think of is when i was installing the CPU intto the 1156 socket. I felt like i had to press down (too) hard to get the latch into its position to hold the CPU down. Could i have pressed too hard, bending the sockets pins or something? They do appear to be angled to an extent.

The mobo doesn't have integrated graphics, so i can't try using no video card.

Thanks in advance

Its most likely a video card issue.
If you have onboard video(ie. a video-out plug on your motherboard) then plug into that and see if it works.
If it does, you need a new video card.

If you dont have onboard video, get a video card from a friends computer and stick it in and try it.

This is rather interesting.
with what you've described it might be the motherboard although i have heard of people having the same symptoms and it being the PSU.
My sympathies.

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