PC problem: Not booting 100% of the time.

[platinum87]

I built a PC for my friend a year ago, he has returned it to me just now saying he is having problems booting it.

So i connected it up, pressed the power button and nothing happens

Kept trying, flipping the power on the PSU/Wall etc, and it turned on and than turned itself off after a 5-6 seconds or so

Eventually It turned on, 1 long beep towards the end, nothing else, and it worked?

I restart/shutdown from windows login screen, all fine, eventually it did not boot when i shut it down.

Now I've managed to boot it again and its in the bios menu for the last hour.

I have no idea whats the problem, i've checked all connections and they are not loose etc, Im thinking either faulty motherboard or faulty PSU?

Any advice on what tests i should run? (i have no tools to check voltages etc)

Here are specs (no overclocking etc going on here all default settings)

i5-4670K 3.40GHz
Gigabyte Z87-D3HP Intel Z87 (Socket 1150)
Seasonic G series 550w '80 Plus Gold' Modular Power Supply
TeamGroup Vulcan ORANGE 8GB (2x4GB) DDR3 PC3-12800C9 1600MHz
Sapphire 270X Boost

 

[wazza300]

Try latest BIOS if your not already running it,

 

[platinum87]

Try latest BIOS if your not already running it,

Will try that tomorrow but nothing has changed and its been working fine for 1 year