This was an interesting error, Windows 64 version 27.7 build 2:

Iteration: 2768128/31272611, ERROR: ROUND OFF (5.219543642e+180) > 0.40
Continuing from last save file.

Now every iteration I get:

Iteration: 17076000 / 31272611 [54.60%]. Per iteration time: 0.031 sec.
Possible hardware errors have occurred during the test! 1 ROUNDOFF > 0.4.
Confidence in final result is fair.

What causes such a massive roundoff error? I'm hoping this DC is worth the effort....

Is this a multi-threaded LL test? If so, there was a bug fixed in 27.9 that displayed massive roundoff errors such as yours. The bug did not affect the final result of the LL test.

[QUOTE=richs;366633]
Iteration: 2768128/31272611, ERROR: ROUND OFF (5.219543642e+180) > 0.40[/QUOTE]
Please update to v27.9, or 28.3, there was a bug fixed for the case when you run one worker in many cores. You can read in the current thread, starting with [URL="http://www.mersenneforum.org/showthread.php?p=305245"]post 71[/URL] more details.

edit: whoops! George was faster (I opened the "reply" earlier, I didn't reply/post because of busy-bees here, now is lunch break)

How do I get multiple worker windows to cooperate on the same exponent? I read that this was possible but cannot figure out how to do it.

Also, is there any way to get prime95 to work on a list of exponents? So far I have had to just enter them in manually one at a time.

The DC completed successfully. I will update my version. Thanks for the advice!

P.S. - The download software page shows two links for Windows 64-bit software under Upgrade Instructions for Existing Users. The second link should be labelled Windows 32-bit.

[QUOTE=richs;366633]This was an interesting error, Windows 64 version 27.7 build 2:

Iteration: 2768128/31272611, ERROR: ROUND OFF (5.219543642e+180) > 0.40
Continuing from last save file.

Now every iteration I get:

Iteration: 17076000 / 31272611 [54.60%]. Per iteration time: 0.031 sec.
Possible hardware errors have occurred during the test! 1 ROUNDOFF > 0.4.
Confidence in final result is fair.

What causes such a massive roundoff error? I'm hoping this DC is worth the effort....[/QUOTE]