I found that Intel did have a sloppy PCIE board solution but only two big companies offered it and it would not have worked on a Mac Pro as we don't have the GPIO header to connect it to
http://blogs.intel.com/technology/2...herboards-desktops-and-workstation-computers/
A cleaner solution would have had the necessary hardware on the PCIE board and only transferred data to the CPU - a cut down Thunderbolt without the display port video channel. But that's not going to happen.
It just seems like they want to keep TB exclusive.
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You are right a MP 5,1 takes up less space than a PC and a nMP and i did consider that route. I already had the PC and a Mac Mini - use the mini as my main desktop and the PC for VMware and games. My requirements changed a little though and i found myself with less time for gaming, instead having to spend more time in VMware. I needed more than 32GB RAM that PC had and I was suffering from an explosion of kit all over the place. After a long debate with myself I decided that it wasn't worth buying a 5,1 MP as I already had external Thunderbolt storage on the mini. If I didn't already have the storage then I probably would have gone for the 5,1 MP (12 core), maxed out the RAM and put some 1TB SSD's in there.
Makes sense I suppose. Dang its expensive to go Mac!