PC shuts down at high memory loads

[HernanVergassola]

So, 2 months ago i upgraded my old R5 2400g for a R7 5700x. Then my PC started to shut down while putting big loads on the RAM. OCCT CPU/RAM tests, Memtest86 and Prime95 Large FFT test (not the other ones) would cause the same problem. This didnt happen with my old CPU, so i RMA'D the 5700x. AMD Sent me another one and im having THE SAME PROBLEM. The thing is, PC doesnt shut down when only one RAM stick is running, only happens with two. I tried lowering RAM speed from 2666 to 1866 and now PC Is more stable (ran Memtest86 and Prime95 without problems), but it didnt solve the problem. I dont really know what the problem could be, maybe is the RAM sticks?

 

Specs:

Ryzen 7 5700x

2x 8gb Micron Crucial Ballistix Sport LT BLS8G4D26BFSBK 2666

AsRock A320m-HDV R4.0 (BIOS L8.01)

ZOTAC GTX 1660

Sentey Steel nitro power 550w SNP550-HM

Windows 11 64 bit