P4C800-E
- 875 chipset - capable of 25% overclock without video artifacts
- uses unbuffered memory, either with or without ECC - ECC allows
error checking, for server type applications
- gigabit ethernet chip connected to private bus (CSA). Allows
network access to occur without affecting other PCI bus activities.
P4P800-e
- 865 chipset - Asus "hyperpath" feature, is a hack to the chipset
that allows the same optimization as the "PAT" feature officially
supported on the 875 chipset.
- uses unbuffered memory, but will not use any ECC info, if it is
present on the DIMM. (You could plug an unbuffered ECC DIMM into
the socket, but the ECC bits would be ignored.)
I see a trivial difference in the AC97 audio chips, optical
SPDIF on the P4P800-E.
If you are interested in overclocking a board that uses the
865PE northbridge, i recommend you read this first.
http://www.abxzone.com/forums/showthread.php?t=62275
If you are not planning on overclocking, either board is
a good choice. The use of the private bus (CSA) for the
Ethernet chip, is generally useful in a server type application,
like if you use the P4C800-E as a SOHO file server.
If this board is being used for your desktop, there aren't too
many normal surfing, email, office application scenarios that
will benefit from the P4C800-E's features. The same is true of
the inclusion of ECC protection for the memory - memory is
good enough these days, that ECC doesn't have too much utility
on a desktop.
What remains, is the overclocking issue. If you plan on changing
the CPU clock from 200MHz to 250MHz or higher, read the thread
above, and decide whether the P4P800-E would be a good choice
or not.