[Beowulf] choosing a high-speed interconnect

[Chris Sideroff]

I'm sure posing this may raise more questions than answer but which
high-speed interconnect would offer the best 'bang for the buck':

1) myrinet
2) quardics qsnet
3) mellanox infiniband

Currently, our 30 node dual Opteron (MSI K8D Master-FT boards) cluster
uses Gig/E and are looking to upgrade to a faster network. 

As well, what are the components would one need for each setup?  The
reason I ask is for example the Myrinet switches accept different line
cards and am not sure which one to use.  Sorry if this a bit of a newbie
question but I have no experience with any of this kind of hardware. I
am reading the docs for each but thought your feedback would be good.

Thanks

Chris Sideroff