> I also got the "illegal sumout" and it locked up my machine. It did it
> four times in a row at the 6564090 iteration (the lock ups were hard
> locks - had to recycle power to recover).
>
> However, I had my pentium-II 266 overclocked to 333, and when I reset
> the speed back to 266 the problem went away. I have had it overclocked
> for about 5 months now with no problems. I have been running prime95 at
> 333mhz since 16 May 99. After resetting the speed to 266 I went back to
> an older backup file (and lost about 4 hours work) just to make sure I
> am still working with good data. Interesting to note -- the average
> iteration speed at idle (0.275 sec) remained unchanged regardless of the
> CPU speed change. Does overclocking even help?
>
> Maybe this error is a bug, maybe a hardware error, although the latter
> seems more suspect in my case.
I've seen this happen a lot on computers that are either overclocked or just
have a faulty CPU/memory module.
For instance, I've got a nice IBM PPro 200 machine that's been running
NTPrime for nearly a year now, rock solid, nary a problem. On a whim, I
thought I'd see if the machine could handle 233MHz. Everything else ran
okay, NT, Office, etc. but NTPrime started kicking out errors like a
banshee.
Reverted to a backup I had made (I was smart...backed up the whole prime
directory before doing anything...if anything I'm over-cautious) to make
sure I didn't corrupt any results...set the speed back to 200MHz and no
problems since.
I did notice in the prime.log that when errors occur, that info is sent to
the Primenet server.
On that note, Scott...what becomes of info sent indicating errors in the
calculations? Are those exponents flagged in someway, indicating that they
are "suspect"?
Anyway, long and short is that overclocking might seem to work fine, but a
really CPU intensive program like NTPrime/Prime95 is likely to show
problems. Heck, it's a great way to find out if your overclocked system is
really working as well as you thought...just back up any temp files
beforehand so you can revert back to them when/if you start getting errors.
Personally, I'm glad we double-check numbers because some errors are bound
to slip by due to overclocked systems not working right. I've decided that
none of the systems I run NTPrime on should be overclocked, to maintain the
integrity of the results as much as possible.
Aaron
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