GD have a variety of servers that run both the clan servers and dedicated boxes. All our servers are rack mount 1U. We do not use cheaper equipment like Shuttle PCs. Highest spec servers include Dell R610 Dual Quad 96gb ram and SAS enterprise drives, Quad Xeon Dell R210 vii with 32GB Ram and SSD's. All of these are hooked into Cisco switchs and our core router is fed at 10gb.
None of the hardware is overloaded, we have no reason to overload them unlike smaller companies.
Well firstly, we are not resellers, so our prices are generally better.
Having two networks and running our own network infrastructure means we have full network redundancy
Using our own servers gives us a lot more control over setup and allocation of resources for the game servers.