I bought exactly the same HP 2080ti card from ebay for £799 (the brand new jigsaw 24 new cards straight out of an oem HP machine right?).
no dust on it at all, new as described. was really happy, until i found out what the blower was like under high speeds in my case.... my god that thing can take off if i unscrewed it from the case.
so, i done the same thing as you.. looked at alt solutions... i ended up going for an artic xtreme IV air mod. bought a new one for £45 (another bargain) and put it all together very slowly. worked great while the case was open.. really really quiet even at load... then i closed my cooler master Silencio 550 case and it got louder and louder again (epecially with games like Ark). no where near as loud or hot as the original blower card and it boosts over 2000mhz as well (or did when the case was open).
I then went and bought a Palit gaming pro heatsink/fan/backplate used shroud from ebay on another deal, thinking that 2x 90mm fans might be better (rather than the 3 on the xtreme iv). I fit it ok and it looked fine, but the fans run at high speeds only as i only had the 14pin -> 4pin header that came with the xtreme IV to use to power one of the fans (while the other fan got powered from a molex->4pin gpu fan header adapter). that one was also loud.. but i think due to the lack of 14pin adapters on the market to use for that propriatory header on the nvidia pcb. i might have been able to pull out the little nvidia Fan PCB from the old hp shroud, but i wanted all that untouched if i re-sold it or wanted to put it back to stock... would also look weird hanging from the new card setup.
I ended up sticking the xtreme IV back on with some better heat paste (not going liquid metal yet) and i spent a little longer this time on the contact points.
Its fine, but i still think the look of the xtreme IV is a bit.... pants..... and the rigidity of the card itself isnt the best... i do wonder if it'll break lose or bend the PCB in some way if i tighten it more (as the grips that come with the xtreme iv are like little clamps around the outside of the pcb).
i disagree with some of the comments above about the VRM chips not being cooled with the xtreme iv as the 3 fans not only blow on the heatsink, but also go straight through the heatsink directly onto the card. on top of that, the massive thick heatsink style back plate that comes with it (with extra cooling pads) takes some of the vrm heat away above the card from behind to help with cooling those components. its not the best, granted, but i certainly think they get some decent airflow (better than most bundled shrouds).
i think my future is in water cooling like yourself... i may end up going full hog with a decent water block over the whole card (luckily this HP oem card is also oem reference nvidia PCB so should fit most blocks).
when the new ryzen is out i'll upgrade my old intel 4790k and treat the whole thing to a new mesh/open case and if the air flow ends up sorting my xtreme IV fan's out, i may just end up water cooling the cpu alone.
thanks for posting all your thoughts and pictures chaps.... really helps me think about options for this card. i was scared of breaking the thing after yanking it out of its original mount, but seems you guys have done that and more with yours.
my pics are below: