CPU Heatsink spins for a few seconds then stops/motior switches from DVI to analog

I recently built a computer 3 months ago but a few days ago it completely blacked out when I was playing a game, so I opened up the thing up to check if everything was alright, and nothing was changed. I went and bought a new DVI cable because I thought I had a faulty cable, I tried it on two monitors and I ended up getting the same results the monitor would switch from DVI to analog. Then I thought maybe the GPU was acting up so I ended up unpluging all the cables from it and reinstalling them, since I dont have a second PC that could support what I had I couldnt try reinstalling the GPU into a second computer. By that time I noticed that the heatsink began to only spin for about 10 seconds and then completely stop, so likewise I went and checked if heatsink was plugged in and it was so I decided to unplug it and replug it in, again same results. If anyone could help that would be very kind of you guys I can also post the parts list and monitiors if needed. I'm not very good at explaining so sorry if this is kind of sloppy and full of run on sentences. 

So you are saying that the computer starts up, fan starts spinning for a few seconds and then it stops and does nothing? Because if that is the case, with no audio indicating the computer has booted up or anything of the like then something happened while the computer was running the power on self test.

Also would you clarify if it is the cpu heatsink fan or the gpu heatsink fan that starts then stops spinning? And when you say the monitor switches from dvi to analog what is actually happening on the screen? It is giving you some sort of notification that the monitor is now using the vga or something of the sort?

Well yeah I had the case open and the CPU heatsink starts and stops after a couple of seconds, then the monitior just gets the analog notification that switches back and forth between analog and DVI. It doesnt show any notications other then the ones I was talking about. The GPU heatsinks are currently running and I have speakers which I should of spoke of eariler sorry about that, so when I do power on the computer there is no noise, also sorry for the late responce and the run on sentences. 

more information about your system would be handy...

I would say disconnect the psu from the wal, take out the bios battery for a few minutes, put it back in, to completely reset the bios. and try again. if the cpu fan is spinning for a few seconds, and the gpu fans are spinning, then i have a bad feeling that it could be your cpu or motherboard.

If the bios reset does not have any effect, then take everything out of the case, lay the motherboard on its box, install 1 stick of ram, reseat the cpu, and cpu cooler, install the gpu, connect the psu, and fire it up outside the case. due shorten the powerswitch pins for a second, or use the power button, if there is one on the board.

Ah, thank you I finally got around to responding today Im trying that out right now, and if you want any of the specs I can tell you them, thanks for the quick reply.