Solution that worked for me follows:
I have a Sapphire ATI PCI Express 5570 as well and experienced the exact same 0x000000CA BSOD in Windows 7 when trying to install drivers for it. I tried the Catalyst driver on Sapphire's website as well as on ATI's website. I tried Catalyst version 10.4, 10.5, and 10.6 with the same issue. I also tried updating the Optiplex (755) BIOS to A17 and trying various BIOS settings to no avail. The BSOD always occurs when the Catalyst software tries to query the video card.
My work-around was to not let Catalyst query the card. I wish it was as easy as an installation option to avoid the query in the Catalyst install, but of course it can't be that straight-forward. Instead, I let the Catalyst software unzip itself to a location, located the driver .inf files in that location, and manually updated the video card driver (Device Manager->Update Driver->"Let me specify the best driver..."->specify location->etc). Two identically named ATI 5570 drivers presented themselves in the driver selection window, so I chose the first one.
Then I manually installed the Catalyst Control Center by locating just the CCC install files unzipped by the ATI package (I ran two setups, CCC-core I think and another name that resembled CCC-something-or-other. I am probably missing some minor components but the screen resolution, color depth, and CCC features all seem to work fine.
Basically everything works with the exception of some video card DLL warnings if I run the System Score test in Windows 7, though it does come back with what feels like an appropriate score of 5.9 for this card.
As a follow-up: after doing all of those steps the Catalyst Installer ran successfully. I did however end up having to delete the following files to make some lingering occasional errors go away:
c:\windows\system32\coinst.dll
c:\windows\system32\atiuxp64.dll
c:\windows\syswow64\atiumdva.dll
c:\windows\syswow64\atiumdva.cap
I ran into the same issue when first setting up my own Acer H244HQ display over HDMI on my AMD Radeon HD 6970 cards.
The image over an HDMI connection can look as good as a DVI connection, with the right settings. I don't think AMD's CCC defaults to the optimum for monitors over HDMI though.
Keep the underscan/overscan settings as you had before, so the image fills 100% of the display.
Then, try looking at the Pixel Format settings associated with your HDMI display (I forget the actual location in the program where it is but it should be there). You should see a few options for formats: YCbCr, Partial RGB, and Full RGB. YCbCr is probably currently selected as the default. This is a color format typically used for movies, which is fine on a TV, but not good for a computer monitor. Change the setting to Full RGB and click Apply. The image should look much less "washed out" and a lot nicer.
EDIT
Another thing to try, if this doesn't fix the problem, is to adjust your Cleartype settings. Click the Start orb and type "Cleartype" and hit enter, and then follow the instructions in the wizard. This should help make your text much clearer to read.
Best Answer
Disclaimer: It certainly can be software, it could be an issue with dirty power, you could find that there are manufacturer drivers out there that are not the latest, but are tested to be more reliable by users. It could be the power connections are not as well connected as they could be, and that it might not be seated well in the socket. I'm listing things you can test, and ways you can "improve" the situation IF it is the usual cooling issue.
The AMD card is more likely to hit this gpu recover which is a hard fail usually like a few bits of ram total wrong, or processing going awry, usually in high temperatures (probably ram from most of the designs).
Continued overclocking No! :-)
Run furmark test the gpu processor, then test the ram with an artifact testing, always watch the temperatures when doing the hard testing like that. By testing the processing of it "more" with the renders, and testing the ram of it "more" with the artifacts testing, you could see if one aspect of it causes the recover problem. Watch the temperatures and see what temperature it more likely happens in.
Crank up the fan till your ears bleed (100%), and test again, use the furmark or play a game with the fans going full bore.
Try to keep the temperatures displayed to the user below 80*C and see if it still does it.
Sure the GPU is fully capable of surviving some 100*C temperatures, and working fine (so they say) I just don't find that to be true myself, and the rams are often hotter than the GPU in different manufactured designs.
Clean out the dust.
Stop the automated stepping, and create specific profiles for the clock rates. I use "Green" as a Gpu 300- mem300 for desktop and 2d browser, and idling. I use "low" 600 - 600 for watching HD video, minor games that are mostly 2d, and editing and other low GPU difficulty tasks. I use a Stock profile called "Med" I manualy created for games, and I do have a "High" Overclock profile for those tough to render games.
Profiles are then easily accessed via the Catalyst notification tray icon (right click). For me it has always been easier and better to snap to the exact speed I desire, vrses the auto. Some people would find it a pain. My "green" 300-300 setting is lower than the software will even set it.
Potentially fan speed can be locked into manual profiles also, but I am using speedfan and advanced fan control (graphing) to get that automatic my way.
As a last effort when you have nothing to lose and no warranty, and are ready to throw it out, get ram pads, and thermal interface goop like as5 and dissassemble the whole thing, clean it out, change the thermal interfaces so it is new and fresh and clean, and reassemble more carefully than they do when pumping them out on a production line.
Mine works :-) But I breech the warranty right after I test it to be operational, I always use some fan graphing program, like afterburner, atitool (obsolete mostly), or this time it is speedfan, to change the temperature profile. I do not need it cooler than 60* and I do not want it hotter than 80*. I get it in that zone as best as possible.
I find drivers with the least stability complaints and everything goes perfect for years. I avoid updating drivers when it is working properly, unless the update states that it solves specific issues with a game I am having that specific issue with. I would also update if they would give us better control of the thermal profiles without 3rd party software.
The Bclk adjustments on the motherboard over 100 increase the PCI bus speed, I tried for a long time to get minor bclk tweaked just a bit higher like 102 & 105, because it would Push the Video and my raid a little harder. On my motherboard an Asus Hero, changing the bclk never did anything useful and everytime created instabilities that did not show up right away.