Unsure computer fault

[jayrt]

Hello,
Today I booted up my pc, left the room, came back, and had found it had turned itself off (this may be because of a loose input, but i'll include it just to be safe). After another 3 attempts it finally decided to stay on, although, nothing would be displayed on my montior except 'D-sub power saving mode'. All fans of my computer components run fine and I am unable to boot into BIOS. I have tried switching the VGA port from my graphics card to my CPU's intergrated graphics, but no change. My monitor only has a VGA port and all components and monitor are within 3 months old.
My PC specs are:
i5 3570k
GTX 560
Ripjaw 8gb ram
Gigabyte GA-Z77 DS3H
1tb seagate barracuda
500W OCZ CoreXStream
My monitor is:
LG E2242C
Appreciate the time and help, thankyou.

 

[profkefah]

u tried another monitor
u tried changing RAM
u tried another psu

 

[jayrt]

Unfortunately I have no spare components to check for faults

 

[rudi95]

if you have an HD tv in your house you could try make use of the hd port on your graphics card to check if it is indeed the monitor that is broken

 

[mocchan]

Try taking out your GTX560 and using JUST the VGA output on your motherboard. While having your GPU installed, there may be a few features that de-active that on-board video on your motherboard.

If this fails, do you have a DVI-VGA adapter? This may also be used to test your motherboard/GPU for fault.

If all else fails, try what rudi95 has suggested.