I'm really going out on a limb here as most of us would be recommending anything specific... Most of us have one or two cards and recommending specifics can be... problematic if they are no longer available, as none of my cards are. But, this hardware has run since 0810 mostly.
However, that being said I would recommend something low to middle range from nVidia. My best video playback card is the least expensive, fanless nvidia, paid $40 for it. My $600 (when I purchased it) GTi-560 may be more problematic, I've never tried it... it's for gaming
So I recommend an inexpensive nvidia card, that supports vdpau (I think all modern ones do) with HDMI output connectors on it. Avoid anything that has purely DVI output as the adaptors don't always pass audio.
My card is a GT-220 (iirc, it's in a case in the basement running). Please feel free to check my wiki page for more specifics (in the signature line below).
You may have to turn off the integrated graphics in the i7, or you could try to use them if you have an hdmi output on the board. iirc the i7 integrated video was capable of vaapi acceleration. Don't recall for sure though.
So, I know it's not a specific recommendation, but that's my knowledge on what you have and what I would look at.
J.
