The dump is referring to WHEA_UNCORRECTABLE_ERROR (124)... which is more related to a hardware error.
I know you have done memtest.... but please do the memtest again for atleast 6-8 passes.....You would need to do it one RAM stick at a time.. Follow this tutorial
If you dont get any errors on the above, then do a surface scan for HDD with CHKDSK.. Follow this tutorial
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