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Our Benchmarks Prove Its Efficacy, But At What Cost?

External Graphics Over PCIe 3.0? Netstor's NA255A, Reviewed

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.

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