Hello TechSpot! I have the following PC: CPU - Intel® Core i5-4690K 3.5GHz Mobo - Gigabyte GA-Z97-HD3 GPU - Gigabyte AMD/ATI Radeon R9 270X 2GB GDDR5 PCIE GV-R927XOC-2GD Memory - Crucial Ballistix 8GB DDR3 PC3-12800 CL9 KIT OF 2 Cooler - Cooler Master HYPER 212 EVO UNIVERSAL COOLER RR-212E-16PK-R1 HDD - Western Digital CAVIAR Blue 1TB SATA 7200RPM 64MB WD10EZEX PSU - FORTRON FSP ATX 2.3 HYPER 600 600W HYPER 600 NOT Overclocked My problem is that it shuts down for no reason during gaming, video watching, poker playing and even just working with MS Office. I have ran Intel CPU diagnostics tools, which has returned "All Fine" results. I have also done a stress-test to see whether CPU or GPU temps will be out of the ordinary - Max temp I get for CPU is 49 and GPU 55 (pretty good range). Yesterday I have ran memtest for each of my RAM and got 4 errors on the "Hammering" stage. This is from the log file: [MEM ERROR - Data] Test: 13, CPU: 0, Address: B0BFB914, Expected: 00000000, Actual: 00010000 [MEM ERROR - Data] Test: 13, CPU: 0, Address: B26EBD5C, Expected: 00000000, Actual: 00080000 [MEM ERROR - Data] Test: 13, CPU: 0, Address: B7AEB0A4, Expected: 00000000, Actual: 00800000 I have read up and it seems that these error should not cause any PC crashing. Thus, I have only Mobo and PSU left to test/analyze and I am not aware how to do that. Could you please recommend how to test whether my PSU is failing (it looks like it does, because sometimes PC won't start and will just "twitch" fans a little) or mobo is corrupted. Thank you!