Computer sometimes shuts off but mostly shows"no signal "

Hello. My computer is my second one i built. It's specs are: GIGABYTE AMD GA-970A-DS3 AM3+ FX ATX Motherboard and AMD FX-4130 3.8GHz Quad Core AM3+ Unlocked CPU Bundle
WD Blue 500 GB Desktop Hard Drive, Solid Performance for Everyday Computing - 3.5" - Sata 6 Gb/s, 7200RPM, 16MB Cache,
Kingston HyperX Blu 16GB DDR3 1600MHz Kit 2x8GB
I just put a Asus GeForce gtx 750 ti with 2 Gb memory in about 2 months ago.
I originally had windows7 operating system but I have upgraded to 10 about 6 months ago with no problems.
For the last 3 days my computer has: once shut it's self down. A few times the computer is on but it's gone to the no signal message. And now when I turn it on it will start to boot up but when I get to my password screen and I hit enter it will go to no signal. I've read that you can unplug the power cord and press and hold the start button for 20 seconds and I have done that a few times and a very few times it has worked. I try to turn the computer off when I not using it because it's so hot right now and I do not have air conditioning. Oh and I just this morning put on a hyper 212 evo CPU fan because I read the paste on a CPU could get old and while I was changing the paste I figured I'd try the big fan. Just had the stock fan before this. I built this computer in January of 13 back when I had some disposable income and tried to build the best one i could afford at the time. (I play WoW) but money is much tighter now so I'd like a cheap fix if possible. Yes I know I ramble but trying to give the most info I can. Thank you in advance for any help.