Question I get blue screens all the time

[MhN]

Hello! I have a friend's computer. He gave it to me because he keeps getting blue screens in windows. I tested the memories, each slot, different mhz, everything. I did prime95 with furmark at the same time and nothing. I can't understand why he gets bluescreens so randomly. There are some sessions to take from startup, some to take after 20 minutes. Could you please help me? It is a very old pc. I don't really know the details.

 

[Lutfij]

When posting a thread of troubleshooting nature, it's customary to include your full system's specs. Please list the specs to your build like so:
CPU:
CPU cooler:
Motherboard:
Ram:
SSD/HDD:
GPU:
PSU:
Chassis:
OS:
Monitor:
include the age of the PSU apart from it's make and model. BIOS version for your motherboard at this moment of time.

 

[MhN]

CPU: i7 4790
CPU cooler: stock
Motherboard: h81m-k
Ram: 16gb ram 1600mhz, 2 rams,different model,but i tested them separated,and it doesn't seem to be from there
SSD/HDD: kingston 120gb
GPU: rx550
PSU: konig 550w,cables modified by him, something very badly done, but it doesn't seem to be from here either
OS: windows 10 installed now
Monitor:

 

[drivinfast247]

Use only one ram stick in the appropriate slot. Remove the GPU and use iGPU.

Try a better PSU and all cables.