This address is a bit suspect for me, each time visit middlecoins www he have more Mh

I think that only using at least 400-450 units of HD 7990 you can reach that hashing power.
He is for sure working in the factory and each day after work he takes one with him through the backdoor

500 MH/s is equal to 660 R9 280x's at 750k each.
I wonder what the most amount of hashrate ever achieved with a mining Trojan is so far...
500 MH/s is about 8,300 quad-core i7's if you are assuming a CPUminer botnet. For a random distribution of CPUs you would probably need 20,000 of more to hash that fast...
really strange graphic.. hashing power increases constantly