Hardware :

Intel Quad 6600
8GB Ram
Vista Business x64
MoBo: Asus Extreme Striker

First I had the problem to install any version of Vista using all 8GB of Ram (2GB sticks).
The googling for days shows that there is apparently a bug which makes it almost impossible to install Vista on more than 3GB Ram .. although not everybody seems to have the same problem.

Anyway .. installation (any version) also failed with just one 2GB stick ... The only way I was able to install Vista Business (was the only license I had that time) was using 2x1GB ram sticks (same make), run windows update and patch and then reboot using the full 8GB ..

Right .. so Vista now runs rock solid since then... Now I bought a Ultimate license to use it was Media Center as well .. Running upgrade .. finished successfully ... reboot ... bluescreen ...

Only 2x1GB Ram sticks .. bluescreen ... rollback option (wonder why they put the option in the boot menu lol) .. reboot .. solid ...

Well ... Question now is whether this has something to do with the MoBo .. consdeirng that all the available driver are almost a year old ...

Burn Memtest to an ISO/Usb/Floppy, boot to it and let it run a few passes with all your ram in and see if any of it is actually bad.
Other than that, im at a loss to explain it since i have zero experience with Vista x64

Considering that Vista Business is fine I don't think it the Ram per se ...

Well, its been weeks now and I knida solved it.

Basically I can install Vista Ultimate perfectly with SP1 slipstreamed. Another option is to install Business with less then 2GB Ram, install patches, more Ram in, install servicepack and upgrade to Ultimate with slipstreamed SP1 DVD.

For weeks now I am trying to get Ultimate installed in a different way .. its just a no no ...

So WHY Ultimate ends up having a bluescreen every boot ? I don't kow ... Why does SP1 fixes it ? I don't know (cannot even find a related patch inside the SP1 which mentions this behaviour).

All I can do now is waiting for SP1 included DVDs on the marked to buy and then I can make a clean installation ...

I can't say which patch it is specifically. But since SP1 does fix it I would try slipstreaming all of the updates that have been released so far to your install dvd. Here's a link to a website that has an update pack for vista x64 and x86. http://www.ryanvm.net/forum/viewtopic.php?t=5698

Let me know if this works out for you. One of the updates in that pack should fix the 2GB problem.

If that doesn't work I would wait for SP1 final to be released since it seems to fix the problem.

I installed x32 fine with 4gb (3327 avail) without issue. as for why ultimate would BSOD on boot, my only guess would be it might have to do with some of the media center/ehome services that are unique to ultimate. if you have a home premium license available i would gamble that it would show the same problems

That was the first thing I have tried - slipstreaming all hotfixes for Business and Ultimate - no go .. when you check the list of hotfixes from SP1 - half of them are not even available for download ..

Yea - looks like I have to wait - I just hope I can install SP1 over the SP1 RC1 .. if not, I will have to reinstall

And I don't think I would have the same problems with Home Premium as Business works just fine ..

run 32bit and install cpu drivers?

Hopefully you've solved the issue by now - But just in case, the update that solves the memory bug is KB929777

As I said - I have tried the memory bug patch, I have slipstreamed ALL available hotfixes ...

Anyway - no I won't run 32 Bit .. I need the amount of memory which is not supported by 32 Bit ...