Prime95 version 27.3

[Prime95]

An early beta prime95 version 27.3 is available. This version supports 64-bit optimized AVX FFTs. 32-bit AVX FFTs are also a little bit faster. I haven't done full benchmarks so I'm not sure how much faster it is than versions 27.2 or 26.6.

The good/bad news is these FFTs are so fast that they are limited by memory bandwidth -- standard Sandy Bridge CPUs will experience a slow down when running all 4 cores. I'd like to hear from Sandy Bridge-E users to see if they also suffer slow downs when all 4 cores are running.

If you do not have a Sandy Bridge CPU there is absolutely no reason to download this version (especially AMD Bulldozer).

Download links:
Windows 64-bit: ftp://mersenne.org/gimps/p64v273.zip
Windows 32-bit: ftp://mersenne.org/gimps/p95v273.zip
Linux 64-bit: ftp://mersenne.org/gimps/mprime273-linux64.tar.gz
Linux 32-bit: ftp://mersenne.org/gimps/mprime273.tar.gz
Mac OS X: ftp://mersenne.org/gimps/Prime95-MacOSX-273.zip
Source code: ftp://mersenne.org/gimps/source273.zip

My Ubuntu box no longer boots so Linux versions are not available yet.

I addressed several bug reports from LLR users. Please retest cases that caused problems in gwnum 27.2.

[Dubslow]

Originally Posted by Prime95

My Ubuntu box no longer boots so Linux versions are not available yet.

If you can give directions (makefile?), I have gcc 4.5.2. (Assuming no one beats me to it.)

Edit: Having problems downloading source. It gets the first few megabytes before completely stopping.

[Prime95]

P.S. Can a Phenom user check to see if CPU speed detection is any better?

[Jwb52z]

How would you check without googling if you have a Sandy Bridge CPU?

[retina]

Originally Posted by Prime95

P.S. Can a Phenom user check to see if CPU speed detection is any better?

I don't have a Phenom but I tried my Fusion 1.6GHz Dual Core anyway:

AMD E-350 Processor
CPU speed: 3130.84 MHz, 2 cores
CPU features: Prefetch, MMX, SSE, SSE2
L1 cache size: 32 KB
L2 cache size: 512 KB
L1 cache line size: 64 bytes
L2 cache line size: 64 bytes
L1 TLBS: 40
L2 TLBS: 512
Prime95 64-bit version 27.3, RdtscTiming=1

Still says almost double the speed that it should be.

[Dubslow]

Originally Posted by Jwb52z

How would you check without googling if you have a Sandy Bridge CPU?

When and how did you buy it? (If it's more than a year old it's not SB.) If you're running Windows, download CPU-Z, it tells you exactly what the processor is.

[Prime95]

Use Options/CPU. It will say something like Intel Core i3 or i5 or i7 - 2xxx or 3xxx. My Sandy Bridge is an i5-2500K.

[Jwb52z]

Originally Posted by Dubslow

When and how did you buy it? (If it's more than a year old it's not SB.) If you're running Windows, download CPU-Z, it tells you exactly what the processor is.

Ok, I don't have a Sandy Bridge then. Mine is an i7 Q720, which were released in the third quarter of 2009.

[Dubslow]

Originally Posted by Jwb52z

Ok, I don't have a Sandy Bridge then. Mine is an i7 Q720, which were released in the third quarter of 2009.

SB and up are all 2xxx four digit numbers. (Ivy Bridge will be 3xxx, as well as the hexcore SBs, which really makes no sense to me.)

[Prime95]

Originally Posted by Dubslow

If you can give directions (makefile?), I have gcc 4.5.2. (Assuming no one beats me to it.)

You won't get the necessary security files to build an official release. You'll have to wait for me to get my box up and running

[bcp19]

Originally Posted by Prime95

The good/bad news is these FFTs are so fast that they are limited by memory bandwidth -- standard Sandy Bridge CPUs will experience a slow down when running all 4 cores. I'd like to hear from Sandy Bridge-E users to see if they also suffer slow downs when all 4 cores are running.

Tried it out on my 2500k, exp 26000069, 1344K FFT, timing went from .010 to .012. On exp 26214607, 1440k FFT, timing went from .010 to .013. I figure it is the memory bandwidth you mentioned, since it is running 3 cores P95 and 1 core mfaktc. Could also be due to it being overclocked.