Can 2015 15" rMBP w/ M370X run two 4k monitors at 60hz?

I haven't the opportunity to try it, but I don't see why not.

It's a mid-range GPU however, so it would help to clarify what exactly you mean. If you just mean simply plugging them in and having two functional displays both running at identical resolutions and refresh rates, then again, I don't see why not. I have searched related threads and I don't see any reason.

In terms of GPU-intensive tasks though, that card may have trouble pushing two 4K displays simultaneously.

Hope this helps.

 

Curious about this too. Assume that Apple support have left it vague for some reason. Perhaps the (2015)MBPr(11,5) can run 2x UHD(4k)@60Hz via TB2x2 - but only with undemanding applications, or in clam-shell mode.

Some general notes here, but nothing definitive yet:
http://www.everymac.com/systems/app...-to-manually-switch-graphics.html#extdisplays

I think some punters on this forum were sucessfully running 2x Dell-P2715Q monitors on the (2014)MBPr(11,3) - but I don't know how hard they were pushing the performance.

 

Anyone else had a chance to test this yet?
Inquiring minds need to know... (thx).

 

The M370X can definitely run two displays at 3840x2160 at 60hz, however I've no idea at what performance hit.

For example does the fan run constantly? how does the fan go with all three displays? can you watch video on one display and work on another without a performance hit/serious fan spin up? how smooth are animations like El Capitan's mission control? etc.