VIA's P4X266: The Pentium 4 gets DDR

Memory Bandwidth - Linpack

Our analysis starts off with a slew of memory performance benchmarks.  This is mainly to get a handle on what to expect from these three Pentium 4 platforms and exactly what's going on. 

Linpack hasn't been seen in a review at AnandTech in a little while, mainly because we had already explained what was going on in the benchmark countless times.  But now with new platforms, we were eager to dust it off and give it a try.

If you don't remember how to look at this graph from our other reviews just keep in mind that the Pentium 4 CPU only has a 256KB L2 cache.  As the data size gets larger than 256KB it can no longer fit in the CPU's on-die data cache and is forced to go to main memory.  The performance of the application drops along with this drop in memory bandwidth and increase in memory latency. 

The lines to the right of the 330KB marker are what you really want to look at.  As expected, the i850 with it's dual channel RDRAM offers by far the most bandwidth out of the three.  Interestingly enough however, the Pentium 4 makes much better use of DDR SDRAM than the Athlon platforms did in this benchmark (see our Socket-A Chipset Comparison for more details).  At the larger data sizes the P4X266 chipset offers approximately 66% of the performance of the i850, again governed by the chipset's memory bandwidth.

Conveniently enough, the i845 offers 45% of the performance of the i850 in this test.  Does this mean that the P4X266 will perform at 66% of the 850 and the 845 will perform at 45% of its older brother?  In an extremely memory bandwidth hungry application, maybe; but remember that we're still stuck in the theoretical world for now.