R7770 / Win XP pro driver issue - directx not supported help please!

Question

Hi guys sorry to bother you, and for such a long question.
I've just purchased a brand new MSI branded AMD radeon r7770 to replace my nvidia 8800gt graphics card which finally bit the dust last week.
Despite uninstalling the old nVidia drivers, trying the ones that came with the card and downloading and installing the very latest versions from both the AMD and MSI sites, I still cannot get directx to work. At first glance, the drivers look to be installed OK, (the Catalyst Control Center starts up etc) but none of my games run, and the desktop refresh is incredibly slow. KSP's crash log helpfully states that it cannot find the device driver. When I run Dxdiag.exe all the directx diagnostic tags are greyed out and the info box states that the card does not support directx.
The system is pretty ancient but should still be up to the task as it was a well speced gaming PC in its day:
Mboard: Asus P5K3 Deluxe (intel P35 chipset)
CPU:      Intel core2duo Q6600 (quad-core)
mem:     4 gig Corsair ddr3 mem.
PSW:     600W
OS:      Win XP pro SP3
I'm aware that this is an old PCI-E 1.0 board and the card is designed around PCI-E 3.0, but the computer boots up and starts Windows just fine. Both the Bios and Windows detect the R7770 correctly. (I'd have thought if this was an issue - it wouldn't go past POST at all and begin beeping like crazy!)
To muddy the waters still further, as a experiment, I installed an old radeon card for test (a crappy Sapphire hd 2600 pro PCI-E version), which is about the same age as the rest of the system.
I couldn't find the drivers disk initally, so downloaded the relevant ones from Sapphire and AMD. Got EXACTLY the same problem as above: it looks as the drivers have installed but no Directx support (which is daft as I used to use that card games until I could afford to replace it with the 8800)
I tried everything I could think of for hours (including disabling driver signing security, stopping anti-virus software, trolling through the windows/ inf, System32 and System dirctories to weed out anything ATI - you name it) then miraculously found the old drivers for the HD 2600. Installed them with no probem at all - everything worked just as it should!
So, I looks to me like the XP drivers on the web are now garbage. Anyone else have similar problems or know of a workaround?
I'm not exactly rich so can't afford Win 7 or the dreaded Win 8  (which I loath) or a new PC, which is why i'm soldering on with this dinosaur!
The only thing I haven't done is splat Windows and do a clean install, do you think that'll help? If so why did the old radeon drivers work (win has been cleanly re-installed many a time since I last used that card, so there was no legacy junk lurcking in the windows diectory or it's registry)
Do you think I'd have better luck with NVidia? If so could you kindly recommend an alternative from them? I know an R7770 is a bit OTT for such an old system, but they are dirt cheap at the mo and not much more expensive than much less powerful cards.
Anyone have any thoughts about UBuntu? If it is a driver issue or there is no workaround, I may need to consider this route. Trouble is none of my legacy games will run on Linux and i'm not sure virtualization is available for my mboard.
Anyways, thanks for your time and for any suggestions you might make
Regards
Mike

Answer 1

Hi Flex, thanks for the quick reply and for the advice.
In the end i got it going by changing the boot.ini settings.
They were initially set with the /3GB /fastdetect switch to force the WinXp kernal to run in 1GB, and not take up 2GB as is it's default.
It was set that way to stop a 32bit game (KSP) crashing every 10 minutes or so, through lack of addressable memory.
All I did was simply set the boot.ini back to its default and directx sprung to life. I reset it back to 3GB to make sure it wasn't a fluke and as soon as I did, it killed directx again.
Maybe its a driver issue afterall - probably lack of proper XP support by AMD (This dosen't happen with the old- - 2008 vintage - version 4 ATI radeon drivers.) or perhaps its because the card has twice the memory over my old cards and therefore needs to access a higher portion of I/O allocation than is available in 32bit WinXP.
Its all a bit ironic really as i'm finding the R7770 runs like crap under dirx9 - i'm getting about 30% the frame rate of my old Nvida 8800GT and, as I can't use the 3GB switch anymore, it crashes every 5 mins or whenever I play any resource intensive game.
As the crashes are caused by lack of available address spaces under 32 bit systems, I've bitten the bullet and got 64bit Ubuntu. Got this working in the wee small hours last night - including the R7770 using the AMD catalyst drivers for Linux. Hopefully that will sort things out (and gimmie an excuse to learn a proper OS!)
Wish me luck i can see another "steep learning curve" on the horizon!
Cheers
Mike