~3m seems to be limit for "normal pumps".
There were earlier pumps with good performance, like famous Mag3. 1260 is probably going to be a good buy only for Eheim-maniacs. Very tricky soltuions from Swiftech alowed them making nice performing pump at (as nikhsub1 said) ONLY 9W. Flow rate is relatively slow but who cares - head matters. This pump is very small tho. It's too small for its performance in my opinion, so it may "want to jump".

But this way it can fit case, 12V won't kill and if comeone wants less vibrations - proper balast can be added.
Other thing is real performance. I'd check how head and flow look in real water cooling world.
Mag3 was said to have specs as written on it.
Swiftech - dunno, but I neeed to check as my pal needs a good pump for in-case setup.
AquaSzut 001 - rated to be 2000lph, 3m head, submersible. Gives almost exactly 2000 lph on zero load, but head when testing with 1/2" tubing was higher than specified (!) it pumped water on 3.5 metres, I haven't checked if it could hande more casue I'd need some ladder

, but after I closed end of tube with hand and released, water dropped to a lil lower than 3m and went up again. Weird for me, but it looks like some pumps don't pump exactly as much as specified.
Extreme head pumps - clima Grundfos pumps like UP Series 100 or simiiar. But such pumps seem to be too extreme for computer water cooling. My old Grunfos is noiseless and uses about 45Watts (at least I was siad that), I can't test it on comp as I'd need to remove it from my central heating

Anyway it can run on 3 sets up to 90Watts, where on max efficiency it's a real monster. We're running it for 3-floor house @ 45 Watts and it's more than enough.
Normal WC rig wouldn't probably survive 8m head.
Conclusion - there were and there are good 3m pumps. New Eheim is also 3m but imho it won't be so good. There are more powerful pumps, but using unprofessional sux, because they use lots of power. Professionals usually offer too high pressureand they are expensive.