Chip toys with Intel's Core Multiplexing Anti-HT or heat reduction?By Chip Mulligan: Friday 30 June 2006, 12:56IT HAS BEEN widely reported that a mysterious option started showing up on recent versions of BIOSes for the Conroe-capable 975X motherboards: something called "Intel Core Multiplexing technology". When combined with the news that AMD may soon be releasing a technology that uses the resources of both processors on a dual core CPU to boost single thread performance, the obvious conclusion many people arrived at was that this Intel technology was an equivalent. When it was enabled, the system would fail to boot, so nobody has been able to test anything. Well this is pure conjecture, but I’m not so sure myself. First of all there is the fact that Intel has been pushing multi-threaded programming with HT and dual core for quite some time now, and it would be a serious change of direction for them. The second is that AMD has patents on this subject, dating back to 1999, all targeting improving the efficiency of a multi-core processor running un-optimised code, and without needing interference from the operating system. So what could it be if it’s not a reverse HT technology? My personal theory (and it is just that) is that one possibility is that it is something developed for Merom as a way of reducing the hotspots on the chip that you would get when running in single core mode, for example when on battery, and that it is not a performance-enhanced mode targeted at the desktop people. The operating system would see just one processor, but code execution would switch between one core and the other, in order to keep the temperatures down.With the shared L2 cache, it wouldn’t be as hard to achieve this as on Turion X2: you would just need to have some way of keeping the two small L1s synchronised. In comparison, AMD’s technology would still present two processors to the O/S, but the thread’s master core would intelligently start using the resources of the second when they were available and needed by sharing data and synchronisation information between the two cores. Intel’s officials do not typically comment on unreleased products, unless they want to one-up AMD, so I’m not expecting a reply.
