Computer turns on but doesn't boot

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Before getting into the problem, I want to tell you about my PC.
I built (with the help of some pros) this custom PC in September 2014. Never really had any issues with it till now. Or maybe for quite some time now. My PC specs -
AMD FX 6300
GIGABYTE GA 78LMT USB 3
ATI XFX RADEON HD 7770 2GB
2 X 4GB DDR3 RAM (cant remember exactly which brand)
And a Thunder 500W PSU (again, Cant remember exactly which one. Its something along those lines)

Problem - My PC powers on but doesn't boot. This problem may have been addressed before but please help me out. I did take a look at other threads. But none of the solutions actually helped. Okay. So the problem is basically that I turn on my PC (the usual way) do the usual powering the CPU on, turning on the monitor. It powers on. Also hear the "beep". All the lights work. Its basically functioning well. But the problem is on my monitor it says "NO HDMI CABLE CONNECTED" Solution may seem simple but it isn't. HDMI cable works totally fine. Tested it with another PC. Monitor is totally fine as well. In fact, when I use the VGA/D-SUB port instead of the HDMI things work perfectly fine and the monitor shows what it needs to show. I'm 100% sure theres no problems with the hardware. I heard its something to do with the BIOS. Anyways, these are the solutions I tried-

Reset the CMOS (by removing the CMOS battery and putting it back in)
Removed memory card sticks (RAM) and put it into different slots.
Also tried draining the power by long pressing the power button.
Have tried pretty much all the popular solutions.

Please suggest a solution that's not been tried by me.
I would of cared less about the PC. But the thing is I'm a YouTuber and this is my only Computer. Need my BAE to produce content. Please help. Like I said I will give a gift to the person that helps me solve this problem (A 10 USD iTunes card)
Thanks.