Difference between Tesla K40c, K40m, K40s

Maybe not the best forum to ask, but did not see a more appropriate place. So … what is the difference between Tesla K40c, K40m, K40s? It is kind of an issue, the letter is not even mentioned on the device (says just “K40” on the side), yet I needed it to install the driver. As far as I know, there is K40 active and K40 passive. Is this documented somewhere?

I don’t know what K40s is. K40m is the version of K40 that is designed with a passive (no fan) heatsink and it must be used in a server that is properly designed to handle it, as the server is responsible for flow-through cooling of the GPU.

K40c is a very similar product but includes an active fansink. The card is basically responsible for cooling itself, and so can be plugged into a wider variety of platforms, e.g. workstations.

In other respects the cards are very similar. Basic perf specs, memory size, memory bandwidth, etc. should be the same.

K40c is documented here:

Thanks for the response. Btw how do you know that K40c is described in the document you posted? It does not mention “K40c” even once.

If you go to driver download (http://www.nvidia.com/Download/index.aspx?lang=en-us), and choose Tesla from the drop down where GeForce is by default, it offers K40c, K40m, K40s and K40st. It was also my first guess that those will be the active / passive, but then there are the ‘s’ ones …

Now thinking about it, why would there even be a different driver for active / passive cooling version, when the GPU core (and hence also the firmware) is otherwise identical? Other than maybe not raising a red flag upon detecting the cooling fan is not spinning on the passive version :).

I know that K40c is the active card, and the doc I linked is covering the Active Board Spec. If you google K40c, you’ll find plenty of correspondence between K40c and references to “Active”. “Active” in this context means Active heatsink, i.e. a fansink, as opposed to a passive (no fan) heatsink.

Regarding drivers, there shouldn’t be any difference between the driver used for K40c vs. that used for K40m. If you actually drill down on the driver download process, I think you’ll find that this is true - the K40c and K40m lead you to the same download page/same driver. For example, if you choose Linux 64 bit, then regardless of whether you choose K40m, K40c, K40s, K40st, you will be taken to the same download page for linux driver 340.58.

Right, that’s actually true. I guess the driver page was designed to be confusing. Goal accomplished :).

According to the Technical specifications of K40 Active (K40c) and K40 Active (K40m), K40m has a BAR1 size of 16GB whereas K40c’s BAR1 size is 256MB.