USB performance
Our USB transfer speed tests were conducted with a USB 2.0/FireWire external hard drive enclosure connected to a 7,200-RPM Seagate Barracuda 7200.7 hard drive. We tested with HD Tach 3.01's 8MB zone setting.

Intel's USB controller tweaking pays dividends for the P55, which offers higher transfer rates than the X58 across the board. The X58's CPU utilization is predictably lower, of course, but the P55's isn't exactly high at just 4%.

PCI Express performance
We used NTttcp to test PCI Express Ethernet throughput using a Marvell 88E8052-based PCI Express x1 Gigabit Ethernet card.

PCI performance
To test PCI performance, we used the same NTttcp test methods and a PCI Intel GigE NIC.

Again, we see the X58 system's higher core count skewing CPU utilization test results. The P55 and X58 are evenly matched in the PCI Express GigE throughput test, but when we switch to a PCI networking card, the P55 pulls up a little bit slower.