This message was posted on behalf of Intel Corporation
Thanks for your interest in the Intel® RealSense Technology.
We’re sorry to hear that. According to the system requirements for the Intel RealSense Camera SR300, the OS required is Windows 10. I have found this link that suggest to use Librealsense in order to use the SR300 camera with Windows 8.1, however, I have not tried it, and you could try that suggestions and share your results with the community.
Hope this information helps.
There was a report of one person who got their SR-300 working (although with slowness and some errors) with an unsupported spec (an Intel Atom processor) by using an "older" version of the DCM. At the time they wrote their message, there was only one DCM for the SR-300, so my unconfirmed assumption was that they used an F200 DCM with it. The F200 camera and its DCM does work with Windows 8.1.
It is very likely not going to work at all, but if you really feel that you cannot upgrade to Windows 10 at present then you are not likely to lose anything by trying an F200 DCM.
The other very unlikely to work thing you could try is to find the location of the SR-300 driver on your PC, right click on the file and select 'Properties' from the menu. On the Properties window that pops up, select the 'Compatibility' tab and tick the box that says 'Windows 8'. This will try to force the driver to work as a Windows 8 file instead of a Windows 10 one. It probably won't work, but it only takes a minute to try it and find out.