Home build gaming PC -screens of death + game crashes

There are a number of reasons for overheating;
1 HSF not installed correctly [more of a problem with intels than amd; amd type coolers are almost idiot proof]
2 Thermal compound dried out
3 HSF or cooler fan not working
4 Poor airflow in the case
5 High ambient temp
6 System is inside a cabinet or desk and little or no airflow

Without having the system in front of me, it is hard to give you an answer as to why it overheats. You are going to have to investigate and fix the problem.

If you R&R the cooler, I always recommend pulling the motherboard on intel type coolers. AMDs can be done in the case however the intels can be difficult to get all four pushpins seated correctly while in the case.

Those coolers are excellent however they are not the easiest things to install. A system that is not overclocked should not run that warm.
Some common errors when installing a coolermaster;
1 Cooler is not oriented correctly. The fan is blowing air back toward the center of the case rather than toward an exhaust fan
2 Bottom of the cooler or fan is contacting a ram chip or the north bridge heatsink and preventing the cooler from contacting the cpu heat spreader with sufficient force to transfer heat energy
3 There is an alignment pin that must be centered to insure proper alignment and contact
4 Using too much thermal compound. The compound that comes with the coolermaster is thicker than arctic silver and very often people use too much which acts as an insulator impeding the transfer of heat energy.

Sorry - I meant to send the whole file link not the Memtest screenshot
Prime95 stress test 29.10.16 showed:

[Main thread Oct 29 22:05] Mersenne number primality test program version 28.9

[Main thread Oct 29 22:05] Optimizing for CPU architecture: Core i3/i5/i7, L2 cache size: 256 KB, L3

cache size: 6 MB

[Main thread Oct 29 22:05] Starting workers.

[Main thread Oct 29 22:11] Execution halted.

[Oct 29 22:05] Worker starting

[Oct 29 22:05] Setting affinity to run worker on logical CPU #1

[Oct 29 22:05] Beginning a continuous self-test on your computer.

[Oct 29 22:05] Please read stress.txt. Choose Test/Stop to end this test.

[Oct 29 22:05] Test 1, 44000 Lucas-Lehmer iterations of M7471105 using AVX FFT length 384K,

Pass1=384, Pass2=1K.

[Oct 29 22:08] Self-test 384K passed!

[Oct 29 22:08] Test 1, 3200000 Lucas-Lehmer iterations of M172031 using AVX FFT length 8K,

Pass1=128, Pass2=64.

[Oct 29 22:10] FATAL ERROR: Rounding was 0.5, expected less than 0.4

[Oct 29 22:10] Hardware failure detected, consult stress.txt file.

[Oct 29 22:10] Torture Test completed 1 tests in 5 minutes - 1 errors, 0 warnings.

[Oct 29 22:10] Worker stopped.

[Oct 29 22:05] Worker starting

[Oct 29 22:05] Setting affinity to run worker on logical CPU #2

[Oct 29 22:05] Beginning a continuous self-test on your computer.

[Oct 29 22:05] Please read stress.txt. Choose Test/Stop to end this test.

[Oct 29 22:05] Test 1, 44000 Lucas-Lehmer iterations of M7471105 using AVX FFT length 384K,

Pass1=384, Pass2=1K.

[Oct 29 22:08] Self-test 384K passed!

[Oct 29 22:08] Test 1, 3200000 Lucas-Lehmer iterations of M172031 using AVX FFT length 8K,

Pass1=128, Pass2=64.

[Oct 29 22:10] FATAL ERROR: Rounding was 0.5, expected less than 0.4

[Oct 29 22:10] Hardware failure detected, consult stress.txt file.

[Oct 29 22:10] Torture Test completed 1 tests in 5 minutes - 1 errors, 0 warnings.

[Oct 29 22:10] Worker stopped.

[Oct 29 22:05] Worker starting

[Oct 29 22:05] Setting affinity to run worker on logical CPU #3

[Oct 29 22:05] Beginning a continuous self-test on your computer.

[Oct 29 22:05] Please read stress.txt. Choose Test/Stop to end this test.

[Oct 29 22:05] Test 1, 44000 Lucas-Lehmer iterations of M7471105 using AVX FFT length 384K,

Pass1=384, Pass2=1K.

[Oct 29 22:08] Self-test 384K passed!

[Oct 29 22:08] Test 1, 3200000 Lucas-Lehmer iterations of M172031 using AVX FFT length 8K,

Pass1=128, Pass2=64.

[Oct 29 22:10] FATAL ERROR: Rounding was 0.46875, expected less than 0.4

[Oct 29 22:10] Hardware failure detected, consult stress.txt file.

[Oct 29 22:10] Torture Test completed 1 tests in 5 minutes - 1 errors, 0 warnings.

[Oct 29 22:10] Worker stopped.

[Oct 29 22:05] Worker starting

[Oct 29 22:05] Setting affinity to run worker on logical CPU #4

[Oct 29 22:05] Beginning a continuous self-test on your computer.

[Oct 29 22:05] Please read stress.txt. Choose Test/Stop to end this test.

[Oct 29 22:05] Test 1, 44000 Lucas-Lehmer iterations of M7471105 using AVX FFT length 384K,

Pass1=384, Pass2=1K.

[Oct 29 22:08] Test 2, 44000 Lucas-Lehmer iterations of M7471103 using AVX FFT length 384K,

Pass1=384, Pass2=1K.

[Oct 29 22:10] Self-test 384K passed!

[Oct 29 22:10] Test 1, 3200000 Lucas-Lehmer iterations of M172031 using AVX FFT length 8K,

Pass1=128, Pass2=64.

[Oct 29 22:11] FATAL ERROR: Rounding was 0.4921875, expected less than 0.4

[Oct 29 22:11] Hardware failure detected, consult stress.txt file.

[Oct 29 22:11] Torture Test completed 2 tests in 5 minutes - 1 errors, 0 warnings.

[Oct 29 22:11] Worker stopped.

You are definitely receiving cpu errors. This can be caused by a number of reasons;
1 CPU damaged by overheating and or overvolting
2 Motherboard problem/failure
3 Voltage drop under load
4 Overclocking can give errors however I think you said the system is not overclocked

Here is what I would do. First pull your cooler off and reseat the cpu in the socket. Use contact cleaner to clean the pins in the board and the pads on the cpu. Do not use alcohol or rub socket in any way. Contact cleaner can be purchased at any electrical supply store or most real auto parts stores [not autozone or other chain] will have it. Use alcohol to clean the heat spreader of the cpu ie the side against the cooler.
Just spray it on and let it sit until dry. Contact cleaner will dry very quickly so there is almost no wait time. Replace the cpu and install the cooler with new compound. Repeat the test. I [think] asrock has monitoring software on the support page for your mb. I never build with asrock so I am not sure. I believe it is the tuning utility. Install that and run the test again. Watch your voltages ie 12V, 5V, and 3.3V values along with vcore or cpu voltage. Vcore should be constant under a 100% load. If you see it dropping while running prime95, it can be a failing voltage regulator on the mb OR a failing pw supply. If the 12V rail drops under load, that points at a failing pw supply. If the 12V remains constant and the vcore drops, that points at a failing VR [voltage regulator] on the board.