XXHighEnd

From one OS to the other that is.

All,

I had a more complicated story here to lay out what all happened, but it is better to summarize what should be done to avoid anomalies by the upgraded OS.

After such upgrade, if you go to Control Panel - Programs and Features, you may see all the Driver Packages installed; They can be from your video card as a first, and from your MotherBoard drivers if you installed those previously. So, that all still looks to be nicely there, right ?
Well, it is not. Not at all;

What happens - at least at going from native Windows 8 to Windows 8.1, is that this "data" is still there, and the packages will undoubtedly still be installed as such (well, they just are), but that their resulting drivers are NOT active in your newly updated Operating System. This does not go unnoticed, and only to the trained eye it is visible. Or not and SQ is bad. Or delays are implied and not all XXHighEnd settings are possible to the ultimate (latency etc.).
But most easiest might be looking at your Display Adapter Driver through Device Manager and see that it is a "Generic Microsoft Device" which it hardly ever will or can be. So this is your indication, might you not completely trust this post.
And FYI : For me it was quite hard to proove that MoBo chipset, SATA and USB(3) Drivers were "just microsoft". I mean, you can only see when you (finally) succeeded.

What this comes down to is that you need to spend more time in upgrading these drivers than it ever took you to upgrade the OS;
You wil need to uninstall really everything that even the slightest smells like "drivers" (see Control Panel - Programs and Features). This means reboots in between, depending on the driver. Uninstall in the reverse sequence of installing (look at the Install dates and start with the newest).

Next you need to dig up all for Windows 8.1 (which with a very fair chance is different for some Drivers for 8.1 than native 8 !) and install all in the normal sequence again (start with the one you uninstalled latest).
Make explicit notice of INF "drivers" (which merely is info on how to install drivers) which for Windows 8.1 can be different from Windows 8. So, if you don't install this as the very first (this is chipset related), nothing will work out again.

All this took me over two hours (for the ASRock based XXHighEnd PC).

If you can digest what really is needed to let all work well, you'd see that the latter part (installing of MoBo etc. specific Drivers) is always in order after installing a fresh OS. But the real message about this is that you think all is OK after the Upgrade, while it definitely is not. Or let's say that at least things changed to what you intended with your original Driver Installs, which you obviously applied for a reason.
And, like in my case I just noticed things to be slow in a strange fashion and it is easy to think that W8.1 itself is the culprit (ok, in the end it is by means of its upgrade procedure). However, it just is simply those drivers not being active, which indeed is the most hard to check for.

I am not so sure whether these are all commonly known facts, but I did not know them. Yes, we do know that it might not be the best to Upgrade the OS and better have Fresh Installs. But that this would be a simple reason for it - no. And of course it is a plain bug (at least for this W8-W8.1 Upgrade) that the installed packages suggest all is fine.

I hope this helps someone, although it may imply a couple of unforseen hours to spend in a weekend.
Peter

Thanks Peter for the time you have put into this! Given the difficulties you encountered I think I'll stay with native W8, unless there is a definitive consensus that SQ is better with 8.1 or Santa Clause leaves an 8.1 install disc by the PC.

Thanks Peter, I was not even aware about this...

Alain