ScienceMark 2.0, Pifast
Starting off, as always, with a look at memory bandwidth and latency.
Prescotts, according to ScienceMark 2.0, have consistently shown 5% greater bandwidth than rival Northwoods. A case of intelligent prefectching, perhaps. As all Intel CPUs are tested on an i875P motherboard, running dual-channel, low-latency DDR400 memory, there's a possible 6.4GB/s available. AMD's FX-53 gets far closer in realising that bandwidth potential.
We had expected Prescott latency to be a touch higher than, say, the Northwood's. The reasoning lies with the increased latency of L1 data cache. Our results indicate that all four P4s are in the same ball park, which isn't the same park as AMD's Athlon 64 CPUs. They benefit from on-die memory controllers that take the latency-increasing Northbridge out of the equation.
Remember we said the Prescott core gives with one hand (tweaks, larger cache, SSE3) but takes with the other (longer pipeline). Pifast is an example of such architectural behaviour. 3.4GHz Prescott is almost 10% slower than the equivalent Northwood. Try as Intel might, it's hard to mask the detrimental effects of extending the pipeline by over 50%.
