The Mac Pro Review (Late 2013)
by Anand Lal Shimpi on December 31, 2013 3:18 PM ESTThunderbolt 2
The new Mac Pro integrates three Intel Falcon Ridge Thunderbolt 2 controllers. These are the fully configured controllers, each supporting and driving two Thunderbolt 2 connectors on the back of the Pro for a total of 6 ports.
Pairing Thunderbolt 2 with Ivy Bridge EP is a bit tricky as Apple uses Thunderbolt 2 for display output as well as data. Typically you’d route all display through processor graphics, but in the case of IVB-EP there is no integrated graphics core. On a DIY PC you enable display output over Thunderbolt 2 by running an extra cable out of the discrete GPU and into a separate input that muxes the signal with PCIe and ships it out via another port as Thunderbolt. Here’s where Apple’s custom PCB work comes in handy as all of this is done internal to the Mac Pro. The FirePro’s display outputs are available via any two of the six Thunderbolt 2 ports, as well as the lone HDMI port on the back of the Mac Pro.
How does Thunderbolt 2 differ from the original? For starters, it really would’ve been more accurate to call it Thunderbolt 4K. The interface is fully backwards compatible with Thunderbolt 1.0. You can use all previous Thunderbolt peripherals with the Mac Pro. What’s new in TB2 is its support for channel bonding. The original Thunderbolt spec called for 4 independent 10Gbps channels (2 send/2 receive). That meant no individual device could get access to more than 10Gbps of bandwidth, which isn’t enough to send 4K video.
Thunderbolt 2 bonds these channels together to enable 20Gbps in each direction. The total bi-directional bandwidth remains at 40Gbps, but a single device can now use the full 20Gbps. Storage performance should go up if you have enough drives/SSDs to saturate the interface, but more importantly you can now send 4K video over Thunderbolt. Given how big of a focus 4K support is for Apple this round, Thunderbolt 2 mates up nicely with the new Mac Pro.
So far I’ve been able to sustain 1.38GB/s of transfers (11Gbps) over Thunderbolt 2 on the Mac Pro. Due to overhead and PCIe 2.0 limits (16Gbps) you won’t be able to get much closer to the peak rates of Thunderbolt 2.
The impact of chaining a 4K display on Thunderbolt 2 downstream bandwidth
Here’s where the six Thunderbolt 2 and three TB2 controllers come into play. Although you can daisy chain a 4K display onto the back of a Thunderbolt 2 storage device, doing so will severely impact available write bandwidth to that device. Remember that there’s only 20Gbps available in each direction, and running a 3840 x 2160 24bpp display at 60Hz already uses over 14Gbps of bandwidth just for display. I measured less than 4Gbps of bandwidth (~480MB/s) available for writes to a Thunderbolt 2 device downstream from the Mac Pro if it had a 4K display plugged in to it. Read performance remained untouched since display data only flows from host to display, leaving a full 20Gbps available for reads. If you’re going to connect Thunderbolt 2 devices to the Mac Pro as well as a 4K display, you’ll want to make sure that they aren’t on the same chain.
If we start numbering in the top left corner of the 2 x 3 array of Thunderbolt ports and go left to right down the stack, you'll want to first populate ports 1, 2 and 5 before filling in the rest. The diagram below should help simplify:
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stevesup - Wednesday, January 1, 2014 - link
Great review, per usual. Even Leo Laporte couldn't dig out a negative nugget to bash Apple with.milkod2001 - Wednesday, January 1, 2014 - link
In a few months a market will probably be flooded with similar cases. Something like semitransparent case in this shape with decent led lighting could actually look quite nice.Back in Windows Vista times I was working with Mac Pro and iMac as graphic designer. It was a pleasure to work with compared to crappy, slow Vista based Pc.
Now with w7 I can't think about single reason I'd want to spend almost twice for Mac Pro compared to W7 Pc(obviously nobody is forcing me to).
Good job with review Anald.
milkod2001 - Wednesday, January 1, 2014 - link
sorry about misspelled name, can't find edit option for postMat9912 - Wednesday, January 1, 2014 - link
Can someone comment on the power consumption of the new Mac Pro when in standby/sleep mode?knweiss - Thursday, January 2, 2014 - link
You'll find the info in the Mac Pro Environmental Report:http://images.apple.com/environment/reports/docs/M...
nomorespam - Wednesday, January 1, 2014 - link
Any idea why the three networking ports couldn't have been combined into a single PCIe 2.0 lane with a switch/bridge?By my math this comes to at most 3.3Gbps (412MB/s) unidirectional with all three ports saturated.
Is this not a possibility or are there other considerations that make this impractical or undesirable?
I'm thinking it would be really nice to get another 2 (ideally 3 for no bottleneck) of the PCIe 2.0 lanes to the USB 3.0 ports and this seems like a valid way to triple available USB 3.0 bandwidth.
The only other place I can see to steal an additional PCIe 2.0 lane back to get to 4 port bottleneck free USB 3.0 I/O is to take one lane away from the SSD controller?
Surely doing so reduces the bus width and resulting net performance even though the theoretical 1.5GB/s that three PCIe 2.0 lanes provide is still faster than the Mac Pro's shipping SSD's?
Like Neil above, I would also like to know more about IP over thunderbolt 1 and 2 and how it works in the real world today - I would suspect the network stack is not in any way optimized for it at this point.
OreoCookie - Wednesday, January 1, 2014 - link
@AnandAny reason why you haven't posted results on your SSD consistency tests for the Mac Pro?
wozwoz - Wednesday, January 1, 2014 - link
Nice review - though rather too long. Sometimes, less is more :)Unfortunately, what is not answered, and remains 'unknown' is:
* Is a D500 graphics card actually any faster than a D300 in real-world tests? [Note that the D500 has a lower clock speed]
* Since the D700 apparently consumes vastly more power than the D300, how does the graphics card effect noise levels and thermal performance of the entire machine?
I liked your chart of CPU turbo boost, as the number of cores in play changes ... first decent explanation of that issue.
bizarrefish - Wednesday, January 1, 2014 - link
Excellent review Anand, very comprehensive and just what I needed to help seal the decision to buy. I believe some of your benchmarks and stress testing was under Boot Camp Windows correct? I too want to use the system as my main Workstation/PC at home but for occasional gaming also. The system will spend most of its time in OSX but Is the driver support good enough to perform well in Boot Camp for modern gaming needs? Thanks.jackbobevolved - Saturday, April 19, 2014 - link
I got the 12 core D700 model and it works great for gaming. The latest Catalyst drivers installed without issue and performance has been amazing. What really blew me away though was comparing the render and export speed on this machine against my old 3,1 8 core with a Radeon 5870. Several hour exports from FCPX were cut to just minutes.