cex might have the real fancy site and the picture of "their" equipment but that doesn't make them legit!
The blocks they mine show up on the blockchain is what makes their farm legit.
It seems you're rather uninformed on the subject. Which makes it really regrettable you chose to invest money with a service you don't understand.
You see the blocks mined by the GHASH pool which, what a coincidence, offers 0% fee to gather as much outside miners as they can. The issue here is: how much of the total mining power of GHASH is real hardware owned by CEX and how much is hardware owned by outside miners?