I'm having the same problem with a variety of new machines that I have built.
When I RDC into the machine, the display does not update correctly. I get partial images, or refreshes only every 20-30 seconds. It is completely unusable. Eventually, it will even disconnect even though I am logged in.
From RDCing into the machine, it looks like the machine is down, but it is fine. I can connect to it with an monitor and the problem is not visible.
I think it is a problem with my network configuration.
What should I look for to resolve this?
There are two things I'd look at:
Use task manager (Resource Monitor) to monitor processes and check for CPU, RAM, Disk page use on the server. Make sure you do this while at the server though (locally connected to it). For network issues, you might want to do regular pings and see what the latency is, I usually use MTR through as it gives me more information about my connection (Ping/trace route with jitter info). If you see high latency/jitter to the server, you might want to use Wireshark to find out why and where you're seeing the issue at.
Good luck!