I came across this article
by bit-tech.net yesterday. Some of it is old news to many but it was news to me. So, if you want to overclock then you must
buy a 'K' series part. So far so good but if you buy a 'K' series part you lose access to TSX-NI, VT-d and vPro support. Probably not a deal-breaker for most and one does still have virtualisation support via VT-x. It's a close call for me but I'm tending towards foregoing my intended modest overclock (modest because stability and component life are important to me) and opting for the i7-4770 instead. If I don't overclock then I can probably spend less on the motherboard, cooling and memory and use the money saved for faster storage and/or graphics.
Bob.Definitions from the Intel web-site:
Intel® Virtualization Technology for Directed I/O (VT-d) continues from the existing support for IA-32 (VT-x) and Itanium® processor (VT-i) virtualization adding new support for I/O-device virtualization. Intel VT-d can help end users improve security and reliability of the systems and also improve performance of I/O devices in virtualized environments.
Intel® TSX provides a set of instruction set extensions that allow programmers to specify regions of code for transactional synchronization. Programmers can use these extensions to achieve the performance of fine-grain locking while actually programming using coarse-grain locks.
Intel® vPro™ Technology is a set of security and manageability capabilities built into the processor aimed at addressing four critical areas of IT security: 1) Threat management, including protection from rootkits, viruses, and malware 2) Identity and web site access point protection 3) Confidential personal and business data protection 4) Remote and local monitoring, remediation, and repair of PCs and workstations.