You really have to wait longer than 30 minutes to draw conclusions. If it is a 20 core server, than I assume it is 10 hyper-threaded cores with a clock speed in the low 2.0 range. Depending on the clockspeed and the amount of time, I would think that the amount of 7-ch chains will increase by a couple.
If you are getting 1.6 ch/d in data coin then they must have a much lower difficulty. You should be expecting 1 to 2 orders of magnitude lower chain rates for Primecoin.
Please note that this list was taken when difficulty < 10, thus 9-chains were block finding chains. Due to the difficulty being > 10 (but < 11) block finding chains are 10-chains, which results in a lower "chains/d" ratio.
You can not use those values to calculate earnings with the current difficulty. If I had to guess, you will probably get between .08 and .12 chains per day with those processors using that miner. After looking at that screenshot it says right there that you are getting 0.112 chains per day. So about .6 XPM/day according to that calculator.
Mining XPM is not a profitable endeavor unless you have free electricity and hardware.
