Our server can access the Raid at a potential 5Gbit but the server only connects to the switch at 1Gbit, so if the server had 4 port PCI card connected to the switch would it be possible to raise the speed to 4Gbits?
RAID at 5Gb? Something fishy there. No network component has a speed like that.
Aggregating four GigElinks gives you a theoretical cap of something like 3.2Gb/s. You lose efficiency with each link you add on.