superpandapower,
I don't have an X800 Pro - I have an HIS Excalibur X800 XT IceQ II 256MB [PE] which uses an Artic Cooling cooling system. Because of the way the cooling system is constructed it is very noticeably more quiet than the ATI 9800 Pro 256MB I recently upgraded from. Therefore, the sound reduction I got when going from from my 9800 Pro 256 to my Excalibur X800 XT IceQ II 256 PE was probably greater than going from a 9800 Pro 256 to a reference cooler-equipped X800 Pro. The Excalibur X800 XT IceQ II 256 is a reference-design X800 XT 256MB PE card - the cooling system (and a sucky 1-year warranty) are the only other differences. The drivers are the same (I'm running the Catalyst 4.9 drivers now).
If you are not familiar with any of the Artic Cooling units, the systems' incorporate a plastic duct system which draws air in from the front of the card (side facing the front of the case), pushes it through a large heatsink, and then exhausts the heated air out the back of the case, (eliminating a considerable amount of heat which would otherwise collect in the case). Because of the large heatsink and ducting system all of the Excalibur Series are two-slot cards, blocking the slot immediately below the Excalibur card itself.
Below is a link to the HIS web site:
http://www.hisdigital.com/html/iceqpromo_freegame.htm
...and a link to reviews of the HIS Excalibur X800 Pro IceQ II 256MB and the HIS Excalibur X800 XT IceQ II 256MB on the Tom's Hardware Guide web site:
http://graphics.tomshardware.c...ic/20040723/index.html
Finally, I have to say that I am very happy with my HIS Excalibur X800 XT IceQ II 256MB card and would recommend it to anyone who wants a cutting-edge card to play today's games at fast framerates AND WHO DOES NOT CARE ABOUT the R420's (AGP) and R423's (PCI Express) lack of DIRECT-X 9.0c (Pixel Shader 3.0) SUPPORT. Currently there are only a handful of games that actually use SM 3.0 - and game performance differences due to ATI's lack of SM 3.0 support hasn't been an issue yet, but I know that I would have liked to have SM 3.0 support built into the R420 core for the future. ATI and Nvidia's high-end cards are about a draw right now - depending on what game or application you are running they trade places in terms of performance lead.
However, if I were:
(a) Less concerned with graphics card fan noise (as I've grown older I have discovered I like quiet)
(b) Less concerned with heat build-up in my case (run a little cooler and longer, maybe a little faster?)
(c) More concerned about SM 3.0 support (and the added "future-proofness" that comes with that support). In this case the 6800GT IS THE WAY TO GO. Same price as reference X800 Pro cards BUT with 16 pipelines instead of the X800 Pro's 12 PLUS SM 3.0 SUPPORT. Very fast card and better price/value ratio than the X800 Pro. No denying this.
(d) More concerned about getting a longer warranty (While rare, cards do occasionally die unprovoked)
(e) More concerned about price (the HIS Excalibur X800 Pro IceQ II 256MB runs $460.00 (in stock at Super PC Mart and the HIS Excalibur X800 XT IceQ II PE 256MB [currently out of stock] runs $550.00)
(e) An anti-ATI Nvidia fanboy (how childish - just like the AMD vs. Intel camps)
BTW, you probably have this handled already, but do you have adequate case ventilation? Make sure your case fans are drawing cool air in AND exhausting warm air. High internal case temperatures can contribute to extended high fan speeds (and thus greater fan noise) because the CPU and GPU fans are trying to cool the case with "recycled" warm air instead of cooler air drawn from outside the case. Taping-off areas inside the case such as wireloom holes and large slots where warm air inside the case can find it's way back to the case's intake fans (instead of the intake fans' drawing-in fresh air) can go a long way towards reducing the ambient temperature inside a case.