Asus p4p8x underperforming on SETI

I have Asus p4p8x that is doing a SETI work unit in about 6 hours on a
Celeron 2.4g running dual-chanel with a pair of Crucial 128mb pc2100
dimms.

The isseue is this:
Using SetiSpy performance calculator, the times for a P4 1.8G 512k w/
a pair of 256mb pc2100 were spot on [slightly over 4 hours]. The
calculated times on the Celeron were about the same. The higher clock
rate should have made up for the lower prformance of the chip. Also I
lowered the amount of ram so as not to overload the cache. When I
benchmarked using Wintune97 [whitch I'm used to, even if out of date]
the RAM writes seem very slow, but the Copy and Reads seem about here
they should be.

Ideas, Anyone?

Nick G.