There are many reasons why P95 will show errors within a minute. The first thing I recommend is running Memtest86+ V4.2 or V5.x overnight to see if the RAM is good. If you're running the RAM at a frequency above 1866 MHz. try dropping it back to 1866 Mhz. or even 1600 MHz. to see if this fixes the issue. You can also try one DIMM to see if this helps until you sort our the possible multiple issues.
You need to look at the CPU core temp under P95. If it exceeds 65C then you're likely to start getting errors. You also need to observe the CPU frequency and vcore voltage. If the vcore drops to .875V and the frequency to 1400 MHz. then the mobo VRM circuit is probably overheating and throttling the CPU. This can cause a drop in active core count until the VRM cools a bit and then it will cycle up and down constantly.
Building a reliable PC involves more than just assembling the parts. You need to be able to configure all of the BIOS settings appropriately. This can be quite involved and frustrating as it can require a lot of trial and error with stress testing. It is however often the only means to get a 100% reliable PC.