Intel's response to power consumption problems on its highest-speed Pentium 4 models was a band-aid approach, giving the processor more power connections rather than fixing the cause. But the Land Grid Array didn't simply increase pin-count, as the pins were removed from the processor and replaced with flexible contacts in the socket. These contacts can be very fragile, and repeated rebuilds have left many testers with dead boards. Yet the one thing LGA 775 still has going for it is Intel's decision to use it in future Core 2 Duo desktop processors, but only using the latest board revisions. Buyers will want to make certain they're getting a compatible motherboard revision before spending any money.

Supporting the highest-performance processors using the latest motherboard revisions, and with the ability to last at least through several careful rebuilds, LGA775 is an excellent choice for performance enthusiasts. It will also host Intel's first quad core Kentsfield processor later this year, but a bus speed increase to 333 MHz (FSB1333) is likely, so you will need a new motherboard.

Socket 939 (AMD Athlon 64, Athlon 64 X2, Athlon 64 FX)

Like Socket 754, Socket 939 saw its increased pin count based on the addition of direct connections to the memory, in this case by providing the CPU with dual-channel memory support. The increased memory bandwidth made available by using two 64-bit modules in a 128-bit configuration was small but noticeable in the original 939-pin Athlon 64s. Socket 939 also received AMD's first dual-core PC processors, Athlon 64 X2, and two cores are better able to use the extra memory bandwidth than a single core.

Socket 939 is currently being replaced by the new Socket AM2, which supports DDR2 memory. But 939 motherboards are a safe bet because they are mature. Additionally, buyers who already own high-capacity DDR1 memory should find Socket 939 offers the most performance for their upgrade dollar.

As with Socket 754, Socket 939 compatibility issues are mostly limited to early BIOS revisions that do not properly support later cores. Mismatches usually function well enough to allow a BIOS update to be performed, but cautious buyers will check the manufacture's Website first.

Socket AM2 (AMD Athlon 64, Athlon 64 X2, Athlon 64 FX, Sempron)

A change in AMD's on-die memory controller to support DDR2 also required a change in the CPU socket. AMD improved the cooler retention module at the same time, but many coolers are cross-compatible.

Though not immediately showing a noticeable performance advantage, the change from DDR to DDR2 was a preemptive measure to assure that future/faster models would receive adequate memory bandwidth. AM2 supports the latest AMD processors, and support for future cores, makes it a great choice for enthusiasts. Because of its new status, all AM2 motherboards are able to support all current AM2 processors.