Brand new PC stuck in power on/off cycle (soft startup only)

Long time reader, first time poster here so hello!

I'm hoping someone has some idea about this, it's got me scratching my head!

Just built a new machine the first time I fired it up it booted off the Windows DVD and loaded Windows all without issue so before I knew it I was in Windows setting everything up. Temps were good, performance was nothing short of amazing but then... a brick wall of sorts.

After shutting down and coming back later to fire it up it would start and all fans would spin up then within a second or 2 it would power off and then restart a couple of seconds later only to continue this cycle endlessly.

Now, here's where it gets interesting. I switched the I/O switch on the PSU to off to completely cut power, waited a few seconds to discharge the capacitors then flicked it back on. Press the power button and it fires up and boots to Windows without any problem. If I shut down and try to turn it on again it does the same power cycle bizzo. Flicking the PSU switch off and on again fixes it until of course, I shut down again.

I've reset the BIOS, switched the RAM to different slots and even unplugged all hard drives except the boot drive - all to no avail. I have read many things about case shorting, overheating CPU but if anything like that was the issue surely the machine would not start under any circumstances, right?

If anybody has any clues as to what might be going on I'd love to hear your thoughts. Sorry for the long post, I just wanted to give as much detail as I could.

Specs... (all brand spanking new).

CPU: Intel i7 2600K
Motherboard: Asrock Z68 Extreme 4 Gen 3
RAM: 8GB G.Skill Ripjaws
HDD1: OCZ Agility 120GB SSD
HDD2: Samsung Spinpoint F3 1TB
HDD3: Samsung Spinpoint F3 1TB
Optical1: LG Super Multi Blue Bluray ROM - SATA
Optical2: LG DVDRW - SATA
GPU: ATi HIS 6990 4GB
PSU: Antec Trupower 850 watt
Case: Coolermaster HAF 932
OS: W7 Home Premium 64bit OEM

All running at stock.

Thanks in advance!

 

Hi,

I hope someone with more experience will answer.

The one thought I had was either test the motherboard battery or try another one. If the battery was bad it would be a potential difference between starting with no AC power and starting with continuous AC power.

 

I would say it's the motherboard or PSU causing the issue. Do you have another power supply to try? If it was case shorting the board wouldn't boot up into windows most likely after what you did.

 

Thanks for the replies, I was leaning towards something being not right on the motherboard but due to being able to start I figured it was always going to be one of those things that you slap yourself in the forehead for missing :banghead
Turns out it was.

I pushed the reset button only to realise it didn't work so on further investigation it turns out that whil all the other headers are set out as + -, the reset is set out as - + so the header was reversed! Who's bright idea was it to do that?

Anyway, reversed the header, problem solved! :tas

Happy it was nothing serious!

 

Glad you got it sorted!

Thanks for posting the resolution.

 

Hi Big,

The RESET switch is only a single pole momentary push button switch. It makes no difference which way you plug it to the MB. You just fixed something else accidently when you replugged it.

Electronics is capable of 1,000,000 errors per Nano-second!

Good Luck, Jim