Intel's E7500 Plumas hit bandwidth bottleneck

Plumas 7500 claims a 3.2GB/s IO bandwidth but integrators tell the INQUIRER that getting even 10 per cent of this throughput is proving well nigh impossible.

The experience recalls problems with the Intel i850 and i860 chipsets. Intel issued no-fix errata for both of these Pentium 4 chipsets and said that the CPUs were unable to maintain memory transfers to keep up with the venerable PCI bus. The i860 has up to three PCI buses but the 90Mb/s figure is below 10 per cent of the possible capacity.

But back to the 7500. The problems are obviously not confined to third party system integrators. Big Intel partners Dell, IBM and Compaq/HP sell dual Xeon Pentium 4 systems but these use the Grand Champion systems, and not the i7500.

The problem highlights future designs based on PCI Express, which Intel is touting as the bandwidth alkahest.

One integrator suggested that the buses should be placed directly on the MCH to meet performance and cutting out the hop that slows down transfers.

He said it's not just Intel chipsets that have what he described as "abysmal" PCI bus performance. Nvidia and Via chipsets also need fixing so they provide better PCI performance for Gigabut Ethernet and video cards, he noted. µ