5k imac with two 4k displays?

Can anyone confirm that you can use two 4k monitors with a 5k imac? I know it has two thunderbolt monitors but people have told me it can only support one 4k monitor due to the processing power of the CPU and Graphics Card. Essentially im trying to have a mac with 3 high resolution displays. I dont know if its possible yet because of hardware limitations. I was thinking about doing a 5k imac with two 4k displays or a mac pro with three 4k displays Or if neither are possible, I'd just go with a 5k imac and the 5k dell monitor if the iMac could only support one monitor. Thank you if anyone can answer this because I know its a niche question thats not really speci