I'm trying to connect two machines with gigabit network cards and a gigabit switch. However, the cable between them is currently plain Cat 5 (not 5e or 6). The leads on the network sockets are also rather hurriedly attached. I'm only getting 10/100 speeds, and not gigabit. Is it normally possible to achieve gigabit over cat 5, or do I need to upgrade the cable, or is it more likely that the socket attachments are causing the problem ?