Nice workstation. I was curious so I ran the power usage numbers. Your system uses ~425 Watts. The NVS 310 uses 25 W at max power.
You can also try to manually set your fan speeds. Max fan speed is always really loud. Try setting your case fans to 80% or whatever you can tolerate.
If you want a really nice GPU for computing you can buy a TESLA card, but they are super expensive, only buy them if you need lots of double precision (FP64). In my opinion, if you need FP64, you are probably better off with a GTX Titan Black, which is the pro-sumer version of the tesla K40. It is significantly cheaper and at least theoretically has the same performance.
Thanks for the info! Do I need a piece of software to manually control the fans, or is it buried in the settings somewhere?
I usually do fan controls though BIOS, but it is possible to do it from within the OS.
for Ubuntu: https://askubuntu.com/questions/22108/how-to-control-fan-speed
Also a picture of you cooling setup might help with finding a way to reduce operating temps.
I haven't messed with the cooling at all. It's the stock Z620 setup. I would like the fans to run a little faster though so I can crank up the BOINC CPU-Time to 100% without worrying about heat.
I still have trouble installing software on Ubuntu if it doesn't exist in the Ubuntu Software Store :-) I'm very new...
I installed lmsensors and fancontrol using Synaptic Package Manager, now I'll work through the setup process in that link.
EDIT: I ran into an error "there are no pwn-capable sensor modules installed". I'll try to do it through the bios
Ubuntu sensors don't work with every motherboard. There are a couple of ways to continue:
Looking at the setup of the Z620, the CPU heat sinks and case fans are all look proprietary. All you can do to improve thermal performance is clean out any dust in the heat sinks and possibly replace the thermal paste on the CPUs.