The server we sell is packaged with software we wrote that makes administering significantly easier. We also provide technical support and even a limited amount of free machine learning consulting. The customers who purchase this server want a headache free solution and aren't as price sensitive as a lone researcher.
notice the custom part box accounts for two more GPUs, I'm not sure why the site doesn't let you add 4 to the GPU section.
This setup ranges from $5250 with 4 GPU to $3240 with 1 GPU. You might want to bump up the PSU for 4 GPU its currently 1500 watts, which may or may not be enough at max load. The article shows a max of ~2800 watts with 8 GPUs
Mobo does not support 4x16 PCIe lanes (that's why they didn't want you to add 4 GPU cards).
Mobo is limited to 64GB RAM.
$520 for two 256GB 840 Pro SSDs? Seriously?
Here's a better mobo: https://www.amazon.com/Motherboards-X99-E-WS-USB-3-1/dp/B00X...
Also, you can literally double the RAM for the same money: http://www.ebay.com/itm/128gb-DDR4-8-Crucial-16gb-DDR4-2400m... (keep in mind that speed of RAM is irrelevant for DL tasks).