Question Not sure if RAM might be the issue here, constant freezes and bluescreens

Oct 14, 2021
I've been having some random bluescreens and game crashes recently and I've now isolated the variables down to two main culprits: the motherboard and the RAM.
Here are my specs:
CPU: Intel i5-11600K
Mobo: Gigabyte Z590 UD AC
(NOTE: first PCI-E slot was malfunctional (bsod/reboot loops) but the second slot seems functional. Not sure if these (more infrequent) BSODs are from a malfunctioning mobo though.)
RAM: Teamgroup DDR4 2666 (from another computer. I took it from an older build, put it in an antistatic bag and bubble wrap, and brought it to America as carry-on luggage)

Errors: random BSODs (Kmode exception not handled, irql not less or equal, page fault in nonpaged area, dpc watchdog violation)
Game crashes (LoL, Apex, Destiny): All of them point to 0xC0000005, access violation error, which can range from faulty ram to corrupted system files.
So far I have: ran disk check, ran memtest86 several times (all passed), ran windows memory diagnostics, sfc /scannow, DISM /restorehealth, reset windows, ran as admin in all of those games, etc etc.
I've spent around $400 dollars just on repairs and the whole build cost around $1600 to assemble. I'm sick and tired of my computer having issues, but also I don't want to spend another 100 on a new set of RAM and encounter these issues again, so I just want to be sure if this is a RAM issue or something else.
Should I run memtest a couple more times just to be sure, or should I just get a new pair of RAM?
hi, run ram stress test in aida64
sometime memtest doesnt show errors as ram isnt really stressed in there....if aida stress test fails within few minutes, then you will need either increase ram voltage or increase ram tCL value (in bios) or reduce ram frequency by a step lower

if stress test will work (about 5 minutes should be enough), then those BSODs are from drivers