Member Avatar for Qwazil

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
HDD: WD 1Tb, SATA,
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

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  • Latest Post Latest Post by Chirpysniper

Dani AI

Generated

Short diagnostic summary: when a new build immediately powers up or repeatedly cycles as soon as AC is applied, then later shows no video, the highest-yield checks are (1) a PSU that’s tripping on a short or fault, (2) the board being shorted to the case or a bad standoff, or (3) a board/CPU-socket fault that keeps POST from starting. ’s note about video and ’s point about the PSU are both relevant; use them to guide a systematic elimination rather than replacing parts at random.

Step-by-step checks (do them in this order):

  • Bench the board outside the case on a non-conductive surface with only PSU, CPU + cooler, one known-good stick of RAM, and a speaker for beeps. Power on by shorting the front-panel power pins or using the case switch. If the cycling stops or you get POST beeps, the case or standoffs were likely the culprit.
  • Swap the PSU or use a PSU tester/multimeter. A PSU that cycles under load or immediately when switched on is a very common cause here; modular-cable mismatches can kill parts, so only use the PSU’s own cables.
  • Inspect the CPU socket under magnification. Since mentioned feeling extra force on the latch, bent LGA pins are possible. Do not force the CPU back in if pins look misaligned—this is a delicate repair.
  • Reset CMOS (remove battery or use the jumper) and make sure the 24-pin and 4/8-pin CPU power connectors are fully seated and from the same PSU cable set.
  • Add a simple POST speaker if you don’t have one and watch any motherboard LEDs or POST code display (consult the manual).

Safety/caveats: use anti-static precautions, don’t mix modular cables between PSUs, and don’t attempt live PSU probing unless you’re comfortable and equipped. If bench testing with a known-good PSU and minimal parts still yields no POST/beeps and the board cycles, the motherboard (or socket-level damage) is the likely next RMA target.

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Member Avatar for plus2plus

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.

Member Avatar for Chirpysniper

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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