Why I files when adding to the archive 7z, WinRar?

Half experiment, I can not understand the reasons.
Archive a virtual machine image, which is installed Win10. Beating the first big file (vmdk), weighing 3.5 gig. A total volume of 9 gig. The file is compressed with NTFS on NTFS partition, I tried to transfer files to another hard drive.

Windows 7 Pro x64, 7z, 16.04 x64, WinRar x64 5.50.
RAM 8 gig system stability, not really complaining, though ponapihano protective soft order.

In any case - almost all terms during a check of the archive CRC error.

Create an archive with maximum compression in 7z (LZMA). Check the CRC error.
Create RAR5 archive with maximum compression or plain - error CRC.
Squeeze ZIP from the same 7-zip file manager with minimal compression - all fine.
The compression process takes about half an hour.

Otherwise, the computer itself does not a bad show, but duplicate (multiple times) error on the same operation.

How to determine the main culprit?
June 8th 19 at 16:48
2 answers
June 8th 19 at 16:50
Solution
To test the memory for errors.
it seems that the common denominator in successful attempts - a couple of gigs of RAM in the compression process. - larue.Tow commented on June 8th 19 at 16:53
Indeed. Memtest86 found errors in a couple of minutes.
Thanks, such a simple thing even in a head did not come. - larue.Tow commented on June 8th 19 at 16:56
June 8th 19 at 16:52
Solution
In addition to memory to try to drive the CPU using linx, occt, prime95.

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