[CentOS] Slightly OT: PCIe x16 card in x8 slot

Thu Aug 22 14:14:45 UTC 2013
Michael Duvall <michael.duvall at ccur.com>

So, in the ongoing saga of the unusual 1U short-depth
workstation, we have narrowed the field to two choices.
Both entrants are configured with 16GB memory (4x4GB),
two 2.5" drives (1x250GB SSD and 1x1TB HDD),
and an NVIDIA NVS510 graphic card (quad display):

1) SuperMicro 5017R-MF, Xeon E5-2609 processor
2) SuperMicro 5017C-LF, Xeon E3-1220 processor

(I wish SuperMicro had a list of their servers by chassis somewhere.)

I have no preference between the solutions for right now,
though I have a major concern with the second solution;
the PCIe slot is only x8, and the NVS510 is a x16 card.
The vendor assures me that a riser/adapter can be found
to plug the card into the slot, and that it will work, but I am
highly concerned about the performance.  I know nothing
about PCIe (I haven't built a system in 10 years, though I
have read the PCIe Wikipedia entries and some guides);
what kind of performance hit can I expect?


You choices are pretty much equal, although the 5017R-MF has the slower
processor, but larger cache.  Both have four core CPUs.  

I recommend going with the native PCIe x16 slot to take full advantage
of the NVS510, especially if you are going to run four heads and your
application is graphic intensive.

Michael Duvall <michael.duvall at ccur.com>
Concurrent Computer Corporation