I have problem with my computer after half year. When I turn it on, from outlook everything work well like fans, light.... But mostly it does not post anything on the monitor. It always says "No signal".
However sometimes when I turn on it works normally. I notice it only works incase the HDD light is on during booting process.
I tried to test my drive in anther computer and it is fine.
What you are saying is that your computer can not always pass POST.
Post (power on self test) tests motherboard, and short ccts, cpu, ram present, then gfx before you get a splash screen on the monitor
First question is, does your mobo bios support the cpu?
If it does, check again to make sure you heatsink is well secured, and that your gfx card and ram are fully inserted.
If all that is good, you probably have a short circuit. That can be a lot harder to find.
Start by looking for foreign objects and loose screws. While you are at it, give everything a good visual inspection. Sometimes you can see something is wrong, even if you dont know what you are looking at.
A place to give special attention is those cylinders around you chip. They are capacitors. If the top is not flat, even a little bulge, or if they are leaking at all, that's your problem.
If you still haven't found the problem, it's time to start removing things.
Add on cards, other than the gfx is a good place to start.
Leave gfx card, one stick of ram, cpu and heat sink, and keyboard till the end.
The best place to start is by checking that the gfx card and ram are well seated.
you say that you're not getting anything to display to the monitor? did you check the cable to the video card?
When you first start up the PC do you hear beeps? If you do I would suggest using a different monitor if you have one available after checking the the cables on the monitor and at the video card. If you don't find anything wrong with the cabling, testing with a known working monitor would be the next step. That is if you hear the beeps of the motherboard during boot up.
If you don't here the beeps / don't have any diagnositic codes on your mobo then the trouble shooting may become a bit more complex.
Based on what you have said it sounds like the monitor is having a signal related problem, which is either a bad cable, connector, video card or possibly something interior to the monitor.
You do have all your system components plugged into a surge protector right?
Try disconnecting as much as poss and see if starts OK. Most likely is intermittant motherboard problem or failing PSU. PSU can have problem starting, but be fine after initial power up. If you get beep for POST OK, but no signal, is monitor, cable problem ( or video card)