Real data speaks volumes. Before we have it, though, proper conclusions are impossible to formulate, even when the math suggests we're on the right track. Personally, Netstor's TurboBox NA255A turned into an example of that confounding predicament. Before I even started testing, I knew the device's single 16-lane PCI Express 3.0 interface should have given me a wide-enough pipe for multiple GPUs working in parallel without imposing a bottleneck.
But I just had to test a card in a PCI Express slot limited to four lanes of second-gen PCIe in order to validate the TurboBox's results. And the numbers speak for themselves, confirming that this unit successfully externalizes graphics cards for GPU-accelerated compute tasks (or games, though this thing is in no way economical for such a usage model). Using three Radeon HD 7970s, we weren't able to perceive any slow-down compared to cards dropped right onto an X79-based motherboard. Additional testing suggests a fourth card wouldn't have fared any worse, at least in bitcoin mining.

Now, how about this product's value? Netstor is asking about $2,200 for its NA255A. So, right off the bat, ouch. You could build a killer workstation including three Radeon HD 7970s for that much money. Granted, you'd still need to find the right case, the right power supply, a compatible motherboard, and then cool it all. But we're Tom's Hardware; that's what we do. For that reason, we find it hard to imagine where the TurboBox makes sense for a PC builder.
But what about someone working on a Mac Pro? Apple's more limited ecosystem means there is no such thing as a three- or four-way graphics array. This could be one of the only options for enabling multiple GPUs. If massive compute potential is important, you might need to swallow hard and consider Netstor's solution the cost of doing business in Apple's world.
- Netstor TurboBox NA255A: Space For Up To Four GPUs, Externally
- Setup And Overcoming Issues
- Test System And Benchmarks
- Results: General-Purpose GPU
- Results: Medal Of Honor Warfighter
- Results: Crysis 2
- Results: DiRT Showdown
- Results: Metro 2033
- Power And Heat
- Our Benchmarks Prove Its Efficacy, But At What Cost?
Or you could use the $2000 to ditch your mac pro that is years out of date and use the money to buy a pc that is better in pretty much every way.
There are some external GPU cases.
The only issue is that the cheapest is somewhere slightly less than $400.
Please explain to me how an aluminum box, a micro-PSU, and a Thunderbolt-to-PCIE adapter adds up to even $200...
$400-$500 for a slightly longer box with a slightly more capable PSU.
Or you could use the $2000 to ditch your mac pro that is years out of date and use the money to buy a pc that is better in pretty much every way.
Mac/Apple users either don't care about or don't under price/performance . My guess, they won't care about the price, just that it doesn't come in pretty colors.
What additional conclusions could be drawn concerning internal vs external throughput?
Apple users are a select group of users, alot of high school kids and girls use them. Not trying to be funny just an observation. If you buy into the Apple thing you have to do things their way and on their terms. Apple has always been cost prohibitive and too restrictive for me personally.
My sister's thoughts when buying a 13" Macbook:
"If it's light, not battery draining, durable, and works, then it's good enough."
ViDock 4 Plus Overdrive (Two 6-Pin/320W/329mm) $279US Plus $30US Worldwide Shipping
http://www.villageinstruments.com/tiki-index.php?page=ViDock
Unboxing: https://www.youtube.com/watch?v=ymYbE3JawLk
7990 x 2?
Still have one PCI slot open for my phone modem card
$13,800? Check your math- I think you forgot a few titans.
4x NA255A @ $2200 = $8800
16x Titan @ $1000 = $16000
4x Seasonic 1000 @ $230 = $920
Total of $25,720 before adding the custom water loops.
the PLX chips are being used in motherboards long ago , and the whole motherboard with PLX chip is 300$ only .. as a matter of fact the PLX chip is 50$ only
add 50$ for case and power and 50$ for board and cables and 50$ profit
what 2200$ ?
I hope Asrock or Asus make such boxs soon for 200$ and with SLI option as well. ...
who needs a stupid useless Thunderbolt when u can have native external PCIe 16 ?
next stop add that port to a notebook .. one to one PCI 16 x no PLX chip... and notebooks will be desktops