Hi there.
I'm not a technical guru, so forgive me for noobiness beforhand

I'll try to explain as detailed as possible. I used to have this problem some times in the past with this PC but it was very rare. The problem itself is: When I press power button on the PC, the blue light lights up, but the flashing violet light (that means that HDD is loading something afaik) doesn't, I can hear fans working and all, but nothing happens and monitor stays switched off. It used to be very rare, and after switching off PC(by holding the power button, reset doesn't work) and starting it again it was starting up fine again. But now its got worse, it starts that way almost every time and sometimes it takes 3-5 restarts to start up the loading of OS.

I have no idea what can cause this so I'd be glad if somebody would explain or advise something.
Thanks beforehand.

PS: I did a search, couldn't find anything regarding my problem...

Off the top of my head, it sounds like it could be your PSU on the way out.
If possible, try unplugging some components and see if it does it less often.

Would agree on PSU, however it might be worth opening your case and checking for dust around the CPU/fan. Mine had a similar problem, and on occasion would state that a start-up was aborted due to CPU overheat. I cleaned it out and whilst it has not fixed 100% there was a least a dramatic improvement to the point that I can use it now.

I havnt heard any flashing hdd thingy. If its flashing it should be sleeping. Check bios for sleep mode. If its on 3, then its the deepest sleep. Try 1 for example.

Quote from dhinchin :

Would agree on PSU, however it might be worth opening your case and checking for dust around the CPU/fan. Mine had a similar problem, and on occasion would state that a start-up was aborted due to CPU overheat. I cleaned it out and whilst it has not fixed 100% there was a least a dramatic improvement to the point that I can use it now.

Cleaned the dust off from everywhere inside, still the problem remains...

A thing you can try when you have multimeter/voltmeter.

Put voltmeter wires on you Power Supply Units 12volt connector(WITH CORRECT POLARITY) and switch on computer.

If voltage drops dramatically (1volt or more) then you have dead PSU. If it doesn't happen, your PSU is proably ok.

Or you can try another PSU if you have one.

Most likely the MB dying (worn out caps etc.) or broken RAM.

If it starts up rarely it could be a problem with your HD.. so run checkdisk or something (not that it would do any good..).

Or it could be a mobo problem, or as suggested a PSU one. Clean inside your PC with some compressed air and see what happens.