Our tests show that when upgrading to HT by using the adapter of a third-party manufacturer, things can go seriously wrong.

With the iP4 from PowerLeap, two out of four boards (Intel 845EBT and MSI 648Max) refused to work with the current BIOS. Without the adapter, however, they functioned as expected. There were no problems with the boards from AOpen and Gigabyte; both detected a Hyper-Threading CPU and our Windows XP test installation worked irreproachably with both virtual processors.

We are still hoping for a compatibility list on the manufacturer's website; this could make life considerably easier for those who are interested in it. Until then, we would try upgrading a mainboard only if:

• it was bought no more than a few months before the Pentium 4 with HT was released (November 2002);
• it is based on an Intel chipset of the 845 or 850 class and is suitable for 533 MHz FSB;
• a current BIOS is available for the board (i.e., a version whose release date is more recent than that of the Pentium 4 with HT).

With regard to performance, only Hyper-Threading can be recommended; the benchmarks are proof positive of the obvious advantages of this technology. It is not by accident that Intel will soon introduce other Pentium 4 CPUs, which offer HT at even lower clock rates.

Arguments in favor of the PowerLeap adapter solution are the simple installation and the presumably low price: if you take into account the cost for a Pentium 4 with Hyper-Threading, an estimated $20 is suddenly not such a high price to pay. In any case, you should choose an accommodating dealer, who will accept a return of the adapter if the upgrade does not work out.