[Various] Overclocker discovers Xeon E5 V3 Errata, Engineers exploit to unlock Turbo
An overclocker who goes by the handle "Dufus" discovered a bug/Errata in the Haswell-e Xeon line of processors, and engineered and exploit, that allows the processor the turbo all cores to the turbo core clock intended for 1 core. For example the Xeon E5 2683v3 has a maximum turbo clock for all cores of 2.5ghz and a maximum turbo clock of 3ghz for 1 core. This exploit which works on both X99 and C612 boards would allow this processor to turbo all cores to 3ghz or close depending on the board and if it has a configurable TDP limit or not (most c612 boards will discover your bios is limited and TDP is no configurable). The Stilt who, is a well known overclocker, explained the errata like this "Haswell was the first "wide" core from Intel (256-bit FP). In order to preserve power, the Power Management Unit (PMU) power gates the upper 128-bit of the FP when 256-bit instructions are not executed. In somewhere between August and September of 2014 Intel changed the behavior of the Turbo on Haswell. Previously the Turbo behavior was identical regardless if the upper 128-bit of the FP was executing or not (i.e same clocks for 128-bit and 256-bit workloads). In the microcode released in September 2014 the Turbo behavior was changed significantly, from static to workload dependant. In this microcode and all the newer ones the Turbo clocks are exactly the same for 128-bit workloads as before, but significantly lower for 256-bit workloads. On my CPU the difference is 400MHz."
The entire process has been documented over on the Anandtech forums, and some crafty users were able to develop a nifty and easy to follow guide, even for those who are technically challenged with these kinds of things like myself, namely a user who guys by the handle vercety who assembled the most complete and final version of the guide.
Most of the meat of the discovery and workaround can be read about one the first three pages here :https://forums.anandtech.com/threads...xeons.2496647/ and the guide will be one post number 213. All of the files required to do this mod can be found here : http://www80.zippyshare.com/v/U179LJHE/file.html
I was able to recreate and test this mod myself and verify its functionality with breathtaking results
The test system consists of an Asrock EPC612D4I ITX 2011v3 motherboard, and Intel Xeon E5 2683v3 14 core, 16gb of DDR4 sodimm
The Original system without the unlock was able to run Cinebench R15 to the tune of almost 1600 points.
After the Exploit was applied the same system scored a blistering 1903 points in Cinebench R15
To further test I ran Firestrike ultra to retrieve a physics score of 16024 before the exploit was applied
http://www.3dmark.com/fs/11829078
After the exploit the same Firestrike ultra physics score increased to a amazing 19264
http://www.3dmark.com/fs/11978056
benchmarking further only validated the incredible results of the exploit these gentlemen have engineered.
To clalify this Exploit ONLY works with Xeon V3 socket 2011-3 processors. Have fun.
http://i1281.photobucket.com/albums/...psngegqrwx.png
http://i1281.photobucket.com/albums/...ps2itdy7kh.jpg
