In generation Haswell processors support was added instructions TSX - Transactional Synchronization Extensions, - that improve cores due to the possibility of resource allocation between them at the hardware level rather than at the program, as is done traditionally. Teams TSX promise to make the execution of certain types of multi-threaded applications much faster, but so far only programmers will curb all the possibilities of this extension.
However, with the development of TSX, it seems, will have to wait. One of the developers found a malfunction in TSX instructions, subsequently confirmed Intel's own tests and has released a new firmware that completely disables the new instruction set.
It is worth noting that the team TSX aimed primarily for use in server applications, so the ordinary consumers will suffer less. Meanwhile, the first shipments of server processors Haswell-EP support TSX will be locked, but the more advanced Haswell-EX work. This means, incidentally, that the latter has not yet been transferred into mass production.
In the new processor stepping Haswell-EP , TSX will be probably corrected. Intel, however, on this occasion does not allow comments.