Prime95 version 27.7 / 27.9

[Prime95]

Originally Posted by Yuno

it is most common at the 24k fft, it crashed once on stock speed too crash as in "prime95 has encountered an error etc" crash. i think small fft should default to 8k ~ 32k instead of 16k the caches of modern cpus have grown a lot, 24k is much more stressful than 8k or 16k.

Unless the crash occurs absolutely every time running the 24k fft test, then the problem is most likely stress related. Sorry, but that applies even if you are running at stock speed.

[JTL]

Originally Posted by Prime95

Yes (and no). There were a few bug fixes between 27.7 and 27.9. These fixes are described in the second post of this thread. Unless you are running multi-threaded FFTs you shouldn't be affected.

Ah I see that post you were referring to. I guess I should have read it more carefully.

Thanks very much for the clarification, Prime95!

[Fahim]

Hello everyone,

I have just joined this forum, it looks very interesting.

I was wondering if anyone faced a similar issue like me. My PC easily goes hours after hours running Prime95 26.6, and everything else that I want to run, and never crashes.

But I downloaded Prime95 27.7 and 27.9, but both of them are crashing my computer within 5-10 minutes of running Prime95. Windows 8 crashes saying something happened and it will restart and a sad smiley on a blue screen.

Any idea why is this happening? I am trying the first torture test ((Maximum FPU Stress)

My system spec is:

AMD FX-8350 Stock
Zalman CNPS9900 Cooling
32GB 2133MHz Kingston HyperX Beast
Windows 8 Pro

Any idea anyone? Thanks a lot in advance.

[kladner]

I'm not sure I can offer any help. I am running 64-bit P95 v27.9, on Windows 7 64-bit. The system is:

FX-8350 @ 4GHz (stock)
Asus Crosshair V Formula Z, 990FX motherboard
32 GB Crucial Ballistix Sport @ 1600

This setup mostly runs 24/7 doing P-1 factoring and dual-GPU LLTF. I have not had P95 crashes or warnings since the last time I messed around with overclocking. At Stock it seems to be rock solid.

[LaurV]

I do not own an AMD cpu, but I have read here around that the AVX on those is slower than the SSE, therefore you should use SSE (klander can confirm or contradict here, what is he running). The difference between the two versions of P95 is that the last one implements the AVX. On Intel cpu's, this translate in additional performance, but which comes with a lot of additional stress for the CPU and heat. Without proper cooling, an intel cpu running v27+ will crash where the same system running v26 will not crash. If (I said "if", some other users can confirm or infirm) the additional heat and stress appears for FX cpu's too (because I understood that the additional performance is yet to be seen on those :P) then you may have a cooling problem. The fan is not properly mounted, or paste is dried, dust clogs, etc. Also, George (or someone else) can confirm/infirm if it is worth to update P95, for your CPU. I still have few core-2 cpu's running v26 and I feel ok with it, George said there is no reason to update to v27-29 on those, as it does not get additional speed (no AVX). If it works, don't fix it.

[kladner]

My impression, (and that is all it is,) is that Prime95 does not enable AVX on FX chips. I suspect that this is part of the "Optimizing for Bulldozer" startup.

I endorse looking elsewhere for the problem.

[LaurV]

Originally Posted by kladner

"Optimizing for Bulldozer" startup.

Oh, it does that? Then it is cleverer than I expected
Honestly I though you use prime.txt options to force SSE or AVX, George said something in the past, but silly me, I didn't pay attention to FX-related because I don't have any.

[Aramis Wyler]

I have 27.9 running on my Athlon X4, and I have not had any trouble with it. It's been running 27.9 for what seems like a long time now, I don't even remember upgrading. x64.

[Kevin]

Originally Posted by Kyle

Hi, mprime 27.9 build 1 Linux64 "crashed" this morning on my computer. It said:

Segmentation fault

and stopped working. Nothing in prime.log. Invoking dmesg, I got:

mprime[35596]: segfault at 7fbb0f2c3938 ip 00007fbc12ad4771 sp 00007fafbbffd010 error 4 in libc-2.12.so[7fbc12a5d000+186000]

I dont know if you can find out the problem with so less informations. It can't be a hardware bug, since the computer memory has 2bit-ECC and temperatures never exceed 45°C.

I had the same thing happen on mprime 27.9 build 1 for 64-bit Linux, after doing ECM on small Mersenne numbers for 2 days.

[Xyzzy]

Using Windows 7, we can run Prime95 on our CPU and mfaktc on our GPU without any lag in the system.

Using Ubuntu 12.04, we cannot. However, we can run four instances of ecm on our CPU and mfaktc on our GPU without lag.

The lag manifests itself when scrolling web pages and popping up new windows. We move from app to app very frequently with ALT+TAB.

We have tried running mprime at the lowest priority. We have tried having it use only three cores instead of four. We have tried P-1 testing and double-check testing. They all lag.

The only solution we can think of is to have mprime "PauseWhileRunning" when the DPMS thingie has not kicked in.

We assume (?) that ecm does not lag because it is not nearly as optimized as mprime. (That does not explain getting lag when running mprime with fewer cores, though.)

We are open to any suggestion to tune our system if we have missed anything. Even if a solution is found, this feature would be a good one and (we think) fairly simple to implement.

FWIW, the system is not an aging laptop. It has an i7 (3770) with HT turned off, a 6GB/S SSD, 16GB of PC3-12800 memory and a Titan video card. (And plenty of cooling!) Things should run lickety-split, right?

PS - we have also adjusted the variables for mfaktc. Surprisingly, we can run 128/8 in Ubuntu whereas in Windows we had to use 32/8 to get decent screen performance. That is pretty odd behavior we think. The way Windows and Linux composes the screen must be very different.

PPS - We run the 2D Unity desktop, so we are probably using less than 1% of the GPU using the desktop or apps or videos.

[James Heinrich]

Originally Posted by Xyzzy

It has an i7 (3770) with HT turned off

For the sake of experimentation, try with HyperThreading turned on. If the source of your lag is competition for CPU resources then HyperThreading should address that very issue.