I've always preferred Intel. In the Pentium II and III days Intel typically had a clear lead, but were usually more expensive. AMD started to pick up a performance lead towards the end of this era. However, I tended to observe that the computers using VIA and SIS chipsets were less reliable than Intel chipsets. When all the processors used Socket 7 (Pentium and AMD K5/K6) you could match an AMD processor to an Intel chipset; once Intel moved to Slot 1 for the Pentium II and the AMD clock rates started climbing, the old Intel chipsets couldn't cope any more leaving VIA and SIS as the only (flaky) choices. It could be that the behaviour of some of the owners of the computers was actually the cause of the flakiness - generally they'd swap components over regularly and install and uninstall a lot of (often slightly dodgy) software. Still, people with Intel systems did the same and they were generally more reliable. Pentium 4 - NetBurst architecture - was an attempt by Intel to massively ramp the clockspeed and it was designed to make best use of fast clocks, by having a long pipeline in which a little progress was made in each stage. If you're not familiar with electronics, it takes a certain amount of time for the signal at the output of a series of logic gates to stabilise at the correct result, or in the case of latch circuits, to latch at the correct result. If the result is sampled too soon (with a faster clock), the incorrect result can be latched and you get incorrect answers. To get the most benefit from this, though, the pipeline needed to be kept filled, and instruction dependencies, memory latency, and branch mispredictions tended to mean that it couldn't be kept full, meaning cycles were wasted. In the case of a dependency error or branch misprediction the whole pipeline has to be thrown away and restarted to recompute the correct operations. The trouble is, the design was intended to ramp to 10GHz and as we know, we never got there - 'NetBurst' Xeons topped out at 3.8GHz or so. The problem was simply heat - too much current was leaking, causing the circuit to consume more power and emit it as heat rather than do useful work. AMD, on the other hand, kept a shorter pipeline consistent with its older models, with larger amounts of work done per cycle. In the end the Athlons were able to clock high enough to surpass the P4s at much lower clock rates. At this point the choice of chipsets for an AMD system appeared to be VIA, nVidia or ATI. nVidia and ATI can't get a video board right (I use which
