No display but pc lights and fans on

I have the pc since end of 2016 and it was working well until recently.

A month ago it was happening the issue of turning on lights and fan, but no display (it didn't even show the bios). Sometimes when I pressed the restart button it turned on. When I unplugged the rams and plugged again the problem stopped happening and worked fine until yesterday. I was using then BSOD happened and the same problem was back, but this time pressing restart button didn't work.

This time I tried the same thing (rams) and didn't work. Tried another slots and using just a single ram, but the problem remains.

I tried changing the hdmi cable to the integrated GPU, didn't work. And unplugged the ssd, same problem persists. Tried resetting the CMOS, nothing changed. The monitor is fine, I used the same hdmi cable into a friend's notebook and it worked.

I took off the VGA and used the integrated graphics, the pc worked normal for a day and the problem happened again.

Any ideas what else can I try and how to discover which hardware is with problem to replace it?

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Specs:

I5 4460. Hyper x Ram 2x4gb ddr3. Motherboard Gigabye ga-b85m. Nvidia PNY gtx 970. Evga 600w. Ssd Kingston 120gb (Windows 10 is in ssd). Hd western digital 1 TB