Broken component – CPU or Graphics Card

My PC has suddenly not outputting anything to my monitors. As soon as I pres the power button, both monitors I have go straight to power saving mode. At first, I thought it was the graphics card, so I took it out, cleaned it, reinserted it but no joy (I do get the green light on the card). I also tried connecting one monitor straight into the motherboard but to no avail. So, now I’m thinking it’s the CPU. It’s an Intel Pentium G3258 overclocked to 4.4GHz. If that was broken, then that would make sense why I have this problem.

Any advice would be greatly appreciated