Prime95 v27.1 Build 1

ftp://mersenne.org/gimps/p95v271.zip

From developer:
A very early pre-beta prime95 version 27.1 is available. It has support for most, but not all AVX FFT lengths. I have not done any of the 64-bit optimizations.

I've been using this version on my Sandy Bridge for the last few days without incident. You are free to do so too. I'm fairly confident it will produce valid results as it has passed some torture testing and QA runs. If you do not have a Sandy Bridge CPU (or maybe a Bulldozer) there is absolutely no reason to download this version. In fact it would be dangerous to do so as I have not tested the SSE2 or x87 FFTs to see if I've broken something!