I/O Bottlenecks on PCI bus?

[Chuck Forsberg WA7KGX N2469R]

Comcast recently doubled my download speed to something
close to 12 mbit/sec.    Now I/O bottlenecks are becoming apparent.

My server has  PCI bus controller cards for two hard drives
and the external network. The local net and the other drives
use motherboard connectors.  Processor is an AMD 6000+
dual core with 8GB memory.

I can run a compute bound process such as Dhrystone with
no noticeable effect on download speed.   However, an
i/o intensive progrma such as quickpar or unrar  accessing
data on local disks served by the PCI interface board
slows incoming data to hafe or a third of normal.

Is the PCI bus that easy to saturate??
Any inexpensive ways to relieve the bottleneck(s)?

-- 
Chuck Forsberg    caf at omen.com   www.omen.com   503-614-0430
Developer of Industrial ZMODEM(Tm) for Embedded Applications
  Omen Technology Inc      "The High Reliability Software"
10255 NW Old Cornelius Pass Portland OR 97231   FAX 629-0665