According to this site http://www.intel.com/support/motherboards/server/se7501wv2/sb/cs-007360.htm the OS you are using is not supported. Being that this has reached the end of life/end of support cycle, best bet is to try the open source community.
Another thing to try is to use an updated NIC driver which may help in this case. Goodluck.
In parallel I tried other things.
I was freightened updating the SR2300 with more recent
firmwares. But disabling aer while loading the kernel in
grub with pci=noaer helped a bit. Then I experienced that
it is no good idea to disable onboard LAN ports. I wanted
to use a PCIe Intel Dual Gigabit NIC only. Now I have four
LAN ports, AER disabled and it works fine. I am of course
only using the LAN ports of my additional PCIe card.
Thanks for everybodies help.
I was really looking into newer platforms from Intel. But I
do wanted to keep my harddiscs (LVD) I recently
purchased and newer platforms all work with SAS/SATA..
SR2300 still gives me great performance. My previous
platform was ISP2150. So this is a big step forward.