Prime95 version 29.4

[pinhodecarlos]

Trying out PRP-CF but I want prime95 to randomly use all threads despite only setting to run on 3. Machine is a 4C/8T. Basically I would like to see the same behaviour (lower temperatures) when I ran LLR with -3 threads. Is it possible?

[ET_]

I installed Prime95 v29.4 b8 on a Toshiba laptop (2 phyical cores, 2.6GHz, Intel 4xxx family) to sunsome PRPs on small numbers.

I noticed that after the first 10,000 iterations, the ms/iter- value grew of about 60%. I thought it was a heating issue (the laptop is thin and the PSU is quite light).

I decided to give a try to the Throttle=n prameter inside prime.txt file, with n=50, 60 and 30.

The best ms/iter. values re achieved using n=30 (1.7 using 2 cores on a 5,9xx,xxx exponent). The ETA value decreased accordingly. Unfortunately, I also noticed that the wallclock time required to complete 10,000 iterations was not 17 seconds (1.7 ms x 10,000) but about 60 seconds (17*0.30).

am I right in stating that the Throttle=n parameter runs the program for n% of the total time, but the ms/iter and ETA values are computed as there were no slowdown?

Luigi
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[Prime95]

Originally Posted by ET_

am I right in stating that the Throttle=n parameter runs the program for n% of the total time, but the ms/iter and ETA values are computed as there were no slowdown?
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That sounds correct.

Throttle may be hard on the CPU. It runs flat out for 1.7ms then idles for 3.5ms.

[ATH]

Instead of throttling in Prime95, you can try the Throttlestop program:
https://www.techpowerup.com/download...-throttlestop/

It will prevent your laptop from throttling but then you have to watch the temperature in the beginnning and lower the multiplier until you reach a speed where it does not overheat. But it has nice builtin view of cpu core temperatures.

I'm still using version 6.00 so I do not know if version 8.60 is good.

[kriesel]

Originally Posted by Prime95

That sounds correct.

Throttle may be hard on the CPU. It runs flat out for 1.7ms then idles for 3.5ms.

I remember seeing prime95's throttling behavior run the cores hard for many seconds and then give them a break, with chip temp changing by more than 10C each time. Now that would be hard on a cpu,all that substantial thermal cycling. Could well have been an earlier release because I saw it on this 8 year old laptop (which still has the original cpu in it).

[Prime95]

Originally Posted by kriesel

I remember seeing prime95's throttling behavior run the cores hard for many seconds and then give them a break, with chip temp changing by more than 10C each time. Now that would be hard on a cpu,all that substantial thermal cycling. Could well have been an earlier release because I saw it on this 8 year old laptop (which still has the original cpu in it).

Your recollection is likely correct. It has been a long time since I looked at that undoc.txt feature. I'm thinking it should be deprecated in a future release.

[kriesel]

Originally Posted by Prime95

Your recollection is likely correct. It has been a long time since I looked at that undoc.txt feature. I'm thinking it should be deprecated in a future release.

What I currently see, with Win64 prime95 V29.4b8, running an ecm curve stage 2, in cpuid HWmonitor 1.35, is 82+-1C, much better I think for thermal stress fatigue on components. I hope this throttling feature remains available for the foreseeable future. I have my 8 year old laptop throttled to 30% and it's running 12W of its nominal 25W TDP. It seems to be gradually deteriorating as I recall using 40-45% throttling a couple years ago, and now it occasionally goes to thermal shutdown when some other intensive activity occurs alongside prime95 at 30%.

[ATH]

From undoc.txt in 29.4b8:

If you want to run the program on several machines this is typically done
by carrying the program and files around on portable media such as a floppy
or USB memory stick. In this case, you need to defeat the program's
automatic detection of hardware changes. To do this, in prime.txt set
FixedHardwareUID=1

If I use this on AWS EC2 instance on startup it still says "CPU identity mismatch" and "ComputerGUID=" in local.txt changes and it creates another CPU on my account. That way you get tons of CPUs on your account, a new one every time you loose your session and it automatically starts a new one.

I'm also wondering what is "HardwareGUID=" in prime.txt compared to "ComputerGUID=" in local.txt? There is also a "WindowsGUID=" in prime.txt but it has no value.

[GP2]

Originally Posted by ATH

If I use this on AWS EC2 instance on startup it still says "CPU identity mismatch" and "ComputerGUID=" in local.txt changes and it creates another CPU on my account. That way you get tons of CPUs on your account, a new one every time you loose your session and it automatically starts a new one.

I'm also wondering what is "HardwareGUID=" in prime.txt compared to "ComputerGUID=" in local.txt? There is also a "WindowsGUID=" in prime.txt but it has no value.

I never did figure out a good solution to this.

I just go to the user account CPUs page once in a while and and clean out the old missing-in-action red-lined records.

But now I notice that that "Merge checked CPUs" has a "date override" checkbox, that seems to be new. So now instead of deleting those old records, I guess you can just merge them together. That used to be impossible because of date conflicts, it didn't want you to merge machines that were running simultaneously.

[ATH]

"date override" seems to work, so that is an option. But it would be nice if we could avoid the creation of new CPUs.

[Citrix]

I am doing some ECM/P-1 work on numbers of the form b^n+-1. Some of these numbers have known small factors.

When I use a large B1 -- most of these small factors are found in the B1 stage and the B2 stage is skipped.

Is this a bug or is there a way to force the program to do the B2 work despite finding a factor in B1?

Thanks.