I'm having a problem with my HDSP 9632. No matter what the buffer size, I get intermittent clicks/pops/minor stuttering/other nasty artefacts (every two or three seconds or so) during audio playback - in BFD2, Cubase or just playing mp3's with Media Player or watching YouTube.

They sound pretty similar to what you could expect when the buffer setting is wrong but changing the buffer doesn't remedy the situation one bit.  I'm running Windows 7 64-bit, a quad-core Phenom II, 4GB RAM and Gigabyte GA-MA770T-UD3P motherboard. All components are brand new including the HDSP which I bought in December.   

I've tried uninstalling/re-installing the latest RME drivers, flashed the firmware, tried to tick all sorts of different boxes in the DSP settings, tried changing settings from the Windows audio panel, made sure the card is correctly in place, tried installing in another PCI slot, checked my power cabling etc. Basically anything I can think of right now. All the drivers (including chipset drivers) in my system are up-to-date.

I have tried both the S/PDIF and analog (headphones) out with similarly disappointing results. My headphones and speakers are working ok. Before my present rig, I had the HDSP 9632 briefly installed in an XP system and also a Win 7 based rig with another motherboard, and I believe there were no such issues. I say "believe" because I only had those two setups for a very short time and didn't really get to experiment. However, the artefacting is so frequent that I'm certain I would have noticed.

E: Multiple edits along the way...