Mined for 6 hours and not find any block with Dual E5 2630 v3 ~ 61Kh/s
http://prntscr.com/i7xy0c

interesting...
http://www.cpu-world.com/CPUs/Xeon/Intel-Xeon%20E5-2630%20v3.html
http://www.cpu-world.com/CPUs/Xeon/Intel-Xeon%20E5-2630%20v4.html

i have 2 theories...

#1. Network difficulty & Network Hashes per second has increased dramatically in the last month...
i´ve seen peaks of 21MH/s
61KH/s = 0.29%

To get a block i think there is a minimum threshold, but don´t know where is it, yet.

#2. the Amdahl law
https://en.wikipedia.org/wiki/Amdahl%27s_law

mined with a 7700K for 4 days, and got 0.
the 77OOk is the 5th fastest Single Core CPU in the world.
https://www.cpu-monkey.com/en/cpu_benchmark-cinebench_r15_single_core-7

#3. Luck based on ping.

i´ve seen weird stuff going on LOL, in the debug mode.