A decent server will facilitate software developing, but a decent server which can be equipped with a GPU is way too expensive. As far as I know, R740 is the only rack server option in Dell series.

But we can have software solution to make use of a cheap R430 server.

Enable OpenCL

https://askubuntu.com/questions/850281/opencl-on-ubuntu-16-04-intel-sandy-bridge-cpu

The information in this article is mainly correct, only it missed the part that content of intel64.icd must be changed to point to the location of libintelcl.so

Enable TensorFlow

Default cpu version tensorflow doesn't work since it lacks some feature. Fortunately, Intel provides an optimized tensorflow which is supposed to enough to use and be faster

https://software.intel.com/en-us/articles/intel-optimization-for-tensorflow-installation-guide