one dual port ethernet card vs. two single port cards for clustering - any advantages/disadvantages

[Micha <michf@post.tau.ac.il>]

I'm looking to setup a cluster for out uni lab and am debating at the moment
for the internal network between the cluster machines (4 machines which are
supposed to be all connected to each other) whether to use on dual port pci-e
ethernet card + one single port pci-e or the onboard card vs. using three single
port pci-e cards and the onboard card as an external internet connection (they
will serve a dual purpuse as cluster machines and workstations)

besides the obvious issue of leaving one (first,third options) or two (second
option) pci-e slots free can anyone tell if there is are any other
considerations that I'm not aware of ? (mainly are there differences in
bus/cpu/speed overheads)

The price difference is not too big (at most 250 NIS per machine for 4
machines) so it may be nice to save the money but only if there are no hidden
performance costs I'm not aware of.

Namely the debate is between

Intel PCI-E 10/100/1000 EXPI9300PT  + (http://www.intel.com/products/desktop/adapters/pro1000pt/pro1000pt-overview.htm)
Intel PCI-E 10/100/1000 EXPI9402PT dual port (http://www.intel.com/products/server/adapters/pro1000pt-dualport/pro1000pt-dualport-overview.htm)

or

Internal Intel 82573E/82573L Gigabit Ethernet controler
Intel PCI-E 10/100/1000 EXPI9402PT dual port
(+ a cheapo 100mb card for Internet connection)

or

Internal Intel 82573E/82573L Gigabit Ethernet controler
Intel PCI-E 10/100/1000 EXPI9300PT x 2
(+ a cheapo 100mb card for Internet connection)

or

Intel PCI-E 10/100/1000 EXPI9300PT x 3

--------------------------------------

The last option has the advantage of a homogenous setup, the second third would
be cheapest the second leaves the most pci-e ports available

thanks