Eh my computer is having a problem to get it turn on
Everytime i press the on button, the light flashed for a sec and it blank off and i press again and nth happened
I have to off the power circult and try again
The same thing happened after many tries
After around 40times try i finally get it working but the next day, the same thing happened. My com is window vista
What is happening?
Someone please help

This sounds like bad caps to me or possibly a faulty power supply. If your lucky you may just have a loose connection inside somewhere or I could be completely wrong about this.

Is this pc new or old?

If it's old then I think it's probably bad capacitors. The caps that go bad most often look kind of like little batteries stuck to the main board. You can normally see the ends of them bulging, some times the even leak.

If it's new then I would say probably loose connections of faulty PSU.

My com is around 2year since i brought it
It is custom build. If it is a loose connection, y i can get it on after multiple tries? Anyways very thankful for ur response

If what your saying is that your computer won't turn on AT ALL, that is no fans are on and nothing is displayed on the screen ect, but after many tries finally turns on.

If this is the case I think you probably have bad capacitors. This is bad news because it not easily fixed. Repairs of this nature should only be carried out by someone that is skilled at soldering. Exact replacements can also be hard to find.

Do you by any chance disconnect your computer from mains power when your not using it? Faulty capacitors often take longer to charge and for this reason pushing the button so many times may work, if only for the time it takes to push the button so may times.

If I'm right I think it may be time to buy a new computer. Of course this is only going by your description and you should be sure before you take any action.