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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LorneKwe - Friday, January 3, 2014 - link
How about we replace those Quadro 6000's with Radeon 7970s which are what the Mac Pro has inside. You can make any price comparison look like shit when you erroneously drop a few thousand dollars worth of GPUs into the build.Dual 6GB 7970s cost $1,400.
Using that, we can build out a 24C Dual Xeon 2697v2 workstation, with 64GB of RAM, dual 512GB 840 Pro SSDs in RAID0, H100i cooling on each CPU, and it would come to around $10,000. Same price as the Mac Pro's kitted out, 12C config, double the CPU power, and a good chunk more GPU power as they aren't underclocked.
You also have the option of going with 4x 7970s if you chose to, and if you forgo to ASUS Z9PE board for a proper workstation board, you can go up to 512GB of RAM instead of being capped at 64GB. If you want dual Quadro K5000s instead of 7970s, raise the PC's price by around $1600, but understand that these will outperform Apple's D700 pair by an enormous margin.
If you're looking for portability, or absolutely require OS X for what you do; choose the Mac Pro. If you're looking for computer power that won't throttle down when faced with tough workloads; have a full-fledged workstation built for you and get much more bang for your buck.
stingerman - Sunday, January 5, 2014 - link
Sorry Dude, this is a Pro Workstation, that mean workstation class GPUs. 7970 is a great CPU but there is a reason it doesn't go into Workstations...madwolfa - Sunday, January 5, 2014 - link
And what is it? Drivers? D700s in Mac Pro don't even have ECC memory enabled in them.wheelhot - Monday, January 6, 2014 - link
yes, the drivers provided (and I believe you can only test this in Windows?) will determine if it's actual workstation class GPUs or just Radeons with the name FirePro slapped on it. I'm seriously hoping it's supplied with actual workstation GPU driver, as it'll greatly benefit the software I use.LorneKwe - Tuesday, January 7, 2014 - link
I'd agree with you if we didn't have solid evidence that Apple's D700 is a repurposed 7970; lack of ECC memory being the best clue, and pricing being a great clue as well.scarhead - Saturday, January 4, 2014 - link
One Xeon E5-2697 processor costs $2,614. Two costs $5,228. I doubt your $3,712 figure for complete system is accurate.p51mustang6 - Thursday, January 2, 2014 - link
Apparently any comment disagreeing with the author gets deleted.chaos215bar2 - Friday, January 3, 2014 - link
Clearly not. Perhaps your comment was rude, trolling, and / or being argumentative without actually adding anything to the discussion?Johan Niklasson - Friday, January 3, 2014 - link
Great review - thanks. I just wanted to add that the new Mac Pro design and its finish does matter more than most people understand. The ones who work on graphic and video applications usually are artists with some sense of beauty and aesthetics. I am sure that the much more pleasant looking Mac Pro is a welcome addition to such people's workspaces.Also the smaller form factor and the silence will make it hard to resist!
james-bond - Friday, January 3, 2014 - link
Thanks for the great review. I wonder if some of the USB ports should have been on the other side of the chassis. Seems like the power cord and monitors are things that are rarely unplugged and are usually on the back side of current case designs. Having to reach around to plug and unplug a flash drive seems inconvenient.Please keep and eye out for an upgrade to Logic Pro (Apple's audio pro app). A would love for you to benchmark this in the same way you did Final Cut. I doubt Apple will be able to harness the second GPU for compute in audio applications do to latency in doing real time audio monitoring. Audio has taken a back seat to video apps in this version of the Mac Pro it seems.