Last time I tried some CUDA work on AWS I spent the best part of a day trying to just get the drivers set up right for a basic test app to work on 14.04 - eventually I gave up and went back to 12.04 which, in 2015, didn't give me much confidence in CUDA as something I can expect decent support for.
sudo apt-get update
sudo apt-get install build-essential linux-image-extra-virtual
sudo reboot
echo options nouveau modeset=0 | sudo tee -a /etc/modprobe.d/nouveau-kms.conf
cat > /etc/modprobe.d/blacklist-nouveau.conf
blacklist nouveau
blacklist lbm-nouveau
options nouveau modeset=0
alias nouveau off
alias lbm-nouveau off
<Ctrl+D>
sudo update-initramfs -u
sudo reboot
sudo apt-get install linux-headers-$(uname -r)
wget http://uk.download.nvidia.com/XFree86/Linux-x86_64/346.35/NVIDIA-Linux-x86_64-346.35.run
chmod +x NVIDIA-Linux-x86_64-346.35.run
sudo ./NVIDIA-Linux-x86_64-346.35.run
nvidia-smi -q | less
This is obviously not production-ready, and is heavily cribbed from online (I couldn't quickly re-find where) but is good enough if you just want to play.EDIT: I think this was the original: http://ubuntuhandbook.org/index.php/2015/01/install-nvidia-3...
Edit:
Looking again at the pricing and specs, it looks like they're just letting you have a full gpgpu box, instead of the multi-tenant box they previously offered where you share with three other people.
Your claim surprised me enough to stand an instance up and take a look for myself. Sure enough, they report having 4 K520 devices.