I noticed no differences at all in regards to performance. I ran both systems with an R9 290 card and ESO performed well even when the card was stupidly running at 95C

No difference .

I upgraded to Windows 10 and a generic NVME drive (from Samsung EVO SSD) and did notice the game looks nicer and is faster.

You ever heard the saying:

"If its not broke don't fix it"

I am going to strongly suggest you stay on Windows 8.1. As an IT professional with experience deploying and working with Windows 10 on 60+ systems...im telling you.....stay on Windows 8.1.

Unless you are running Windows 10 Enterprise, you are on whats called the "Wave Update channel" this means you get to be the beta tester for all the updates, while the Corporate Customers(those on Enterprise versions) get put on the Stable Business Release Channel where they don't get updates like the Anniversary Update for 8-10 months, so by the time they get it, all the issues with it that broke peoples systems(like yours) they don't have to deal with.

Windows 10 also ignores Group Policy settings telling it not to install updates, despite your wishes otherwise. The only way to stop it from installing updates is to be on WSUS(Windows Server Update Services) with an Enterprise version. This is important because non-enterprise users of Windows 10 are on the beta update channel and those updates can break your system or programs that run on your system(like ESO) can stop working due to these beta quality updates...Windows 8.1 Updates are much better tested because it still has quite a large Corporate presence, and shares the same code base with Windows Server 2012 and 2012 R2 that share much of the same codebase so updates are far better vetted then what you will get with Windows 10

Windows 10 also is full of all kinds of telemetry that you can not turn off unless you have the Enterprise version of Windows. This means every keystroke you make, every web site you visit, every file you dowload, every program you run is returned to some server hosted by Microsoft. Every password you enter, every character you type, Windows 10 is literally a keylogger which is always spying on you.

You should never accept this spying willingly. You have a Constitutional Right to Privacy, Don't give it up, Support Open Solutions like OpenGL Vulcan which will be better then DirectX 12 anyways if it gets enough support(Nvidia and AMD are both putting lots of support behind Vulcan)

Windows 8.1 is a far leaner OS over all...it uses about 11% less system RAM compared to Windows 10, logging is significantly faster then Windows 10(because it doesn't have all that telemetry garbage running all the time)

Windows 10 is full of all kinds of "little annoying bugs" just use it for a few months for more then just launching ESO.....

I go home at night from work, and I am thankful I don't have to deal with that POS called Windows 10.

Windows 8.1 was the last Microsoft OS designed by Steven Sinofsky....He left Microsoft shortly after their internal plans for Windows 10....he also lead development of Windows 7....Windows 8.1 was actually a step in the right direction for modern user interfaces....windows 10 is a very big step backwards.....Windows 8.1 addressed all the issues with 8 and was and still is a more sophisticated UI then Windows 10....Furthermore, you can slap Classic Shell on Windows 8.1 and turn it into Windows 7 2nd Edition.....i mean its a win win.

Stay with Windows 8.1 you will thank me for it later, if you decide to take the plunge...good luck...you will be back if you have the disk and opportunity to....im just trying to save you some frustration....Windows 10 is a buggy POS and is the 1st Windows operating system I have dealt with that is impossible to get an event log on boot without any Red Error warnings....Even Windows Vista could be fixed to show no errors just information.

right now the only events in event viewer that fire on my Windows 8.1 machine are "information" events no errors of any kind....the fact its impossible to get Windows 10 to do this is annoying enough as it is...if you decide to move to Windows 10 just now its beta software...only Enterprise Versions get to use the Stable Business Release channell with updates that won't possibly break your system or break programs on your system...at least Windows 8.1 doesn't use beta updates...just saying...good luck

THANKS RinaldoGandolphi.

Since my main use of this PC is gaming I will heed your advice and not upgrade.

I have heard many things about Windows 10 that were uncomplimentary. Many if the Forum posters kept saying "That's a bug and Microsoft will fix it" Of course, these "bugs" are features and intended to be in there. I don't think Microsoft is quite the "Hal" computer in the movie "2001 a Space Odyssey" yet, but..........

I went from win7 to win10 and havn't noticed much of a difference except game load faster and frames are better.