I have run Memtest86 and had some errors show up, but not of the volume you report. I understand the software is very searching but also reliable - generally.
When I ran it I was having problems with Acronis True Image indicating corrupt backups when I validated. Acronis Support advised my RAM was bad, but after a lot of other digging I found this to be untrue and the cause was something else.
However I did find a fair amount of information on Memtest86 and this FAQ click here]FAQ[/url was one of the most informative as it provides information on false positives. Hope it helps.