10GbE Cards not running 10G speeds

I have a Synology RS3412RPxs SAN with an Intel X540-T2 10GbE nic card and a Dell R410 running VMware 5.1 with the X540-T2 as well. I have them directly connected with a CAT6 cable (i have no 10GbE switch) and both devices indicate 10GbE mode connections. But when I try to do transfer from the local datastore to either a iSCSI or NFS datastore on the Synology, I'm only getting 1GbE speeds. I had a X520-T2 before and I tried it between two Windows Server 2012 machines, direct connect again, and file transfers between the two machine was 1GbE also. Am I doing something wrong? Do I need a switch in between? I'm pulling my hair out. Thanks.