I own the HIS HD4870 1gb, and the fan has come completely apart from the card. It seems as though it was a glue job or something and not fixable. Space around my card is always clear, and I tame all cables and wiring in the system. I'm not sure why, other than heat stress over time that this would have happened. I've contacted HIS about getting a fan replacement but they have not replied to me. Is there a way to replace this fan or is my video card garbage now? I'll include a link to an image of what mine looks like.
Not sure about HIS's replacement policy but there are third-party parts that include fans for graphics cards, if it's still under warrenty I would ask HIS about fixing it but since HIS isn't responding I would start looking for those fans.
I don't think the fan on that heatsink can be replaced. Rather you'd have to replace the heatsink and fan. That is, unless you'd be comfortable wire-tying a 60 or 80mm fan to it.
When my 8800GT's fan died, since the stock cooling was crap I got one of these: Akasa Vortexx Neo.
Sidewinder Computers is one of the few places in the US that even sells Akasa products. I got mine there and I don't regret it one bit. That card has never topped 55C since, and I used to see 75C temps regularly using the 8800GT reference cooler. The only possible trouble you could run into is clearance over your VRM heatsink.
This is but one of many replacement VGA coolers that you could consider. However, I do strongly suggest you pursue matters with HIS first. Call them if you must.
I'm still trying to find a cooler for this video card. It has been sitting for months and I just haven't gotten back to it until now. I've been looking online but it seems difficult to find a cooler for this card. I am not sure if I'm going to keep the card or sell it, and don't need anything fancy or expensive. Just something that will do the job like the stock cooler did. I'd like to find something under 50 dollars, or even under 40 if I can.