Hey there. You seem to know a little more about the thunderbolt stuff than an average Joe like myself.. so.. may I ask how you think Apple may implement thunderbolt on a new Mac Pro?
The most straightforward way of doing it is to simply just copy what they did on the iMac. This isn't something Apply hasn't already done. Like the 2012 iMac, solder a decent GPU and VRAM right onto the motherboard. There is no need for a video switch since there is no video coming out of the IOHUB support chip ( which gets it from a mainstream Core i CPU package ).
[ there is some speculation Apple may not have hooked up CPU package on the lower iMacs anyway since they are just Intel HD2500 ( not even HD400) packages. In that case it would be exactly like they did on the iMac. ]
The Mac Pro would be different from the iMac but it would still have 3-4 PCI-e slots. (likely 4). In that sense system is different in that the user can add a
2nd video card and use
both in parallel. In fact, the standard config might just come that way with two GPUs installed by default.
What folks seem to be getting their underwear in a twist over is getting all 2 or more GPUs to pump video data over Thuderbolt. It isn't necessary now when have 2-4 video cards. Should really be necessary when have just one embedded GPU.
Would they have the thunderbolt ports on the back with the rest of the ports?
Two ports just like the iMac. [ there may be some other ports on front USB 3.0 and/or Firewire , but not Thunderbolt. Most likely will loose two legacy ports off the back and replaced with TB. Whether those move to front or disappear is a toss-up. ]
If so, would they support outputting video that is sent via the PCIe GPUs? Or, will the GPU's have the Thunderbolt Ports?
No.
No TB ports on PCI-e card. It is theoretically possible but not practical market wise. Lots of design and certification complexity for extremely limited gains for what would likely be a highly proprietary card.
No virtual GPU because I don't think Apple or graphics makers will allocate the resources. Some third party may step in, but not no 3rd party enhanced/solved the embedded+discrete "at the same time" problem on the laptops. I doubt the much smaller Mac Pro market would draw one of those virtual GPUs vendors in.
Nor does Apple put time into supporting SLI/Crossfire. Again complexity that Apple avoids.
A discrete GPU PCI-e card is perfectly capable of hooking to a monitor by itself. There is extremely narrow added benefit of rerouting that output through Thunderbolt into yet another cable. (stuff like locating the Mac Pro 10 yards away from the monitor and a "need" for fiber Thunderbolt is just appealing to tiny corner case contexts. ) For normal cable lengths hooking to a general monitor is cheaper to just use the normal connections already present on both card and monitor.