I currently am running Windows 10 Pro on 3 PC's. As illogical as this may sound the weakest of the 3, a Dell All in one with Blueray Drive, a 1Tb HDD, an i5 CPU and onboard video card and 4 Gb memory took Windows 10 from Windows 7 like a duck to water.
My laptop is an Alienware M17x with 8 Gb RAM, this has an engineer CPU which I can overclock, dual Ati video cards running in Crossfire, it has 2 SSD drives me 1 is 1 Tb, the other 512 Gb when I went to make the upgrade it failed, I looked up the failure code and did the necessary things required and tried again. Not only did it not work I thought it had bricked the laptop. With frustration I went to my main desktop.
My main desktop PC was a beast when running Windows 7 Ultimate, it has 18 Gb RAM, 3 1.5 Tb HDD's and a 1 Tb SSD, an Ati 5970 dual video card with 4 Gb RAM running in Crossfire mode, 2 Blueray burners, one good for burning 25 Gb RWBD's the other 50 Gb RWBD's, i7 975 CPU factory over locked, and more than I need to mention. Ran into the same issues with it as I did with the laptop so I now had 2 bricked machines.
I knew my machines were healthy since there were no issues when running Windows 7 Pro on the laptop and Ultimate on the desktop si with Windows 7 disk in hand for each machine I went about the task of repairing the Windows 7 on each.
It worked but not like prior trying to upgrade to Windows 10. I decided to remove my A/V program Avast on each, download Malwarebytes ( had to do this in safe mode for some reason ), ran Malwarebytes on each and was shocked to find the intrusions I did since I knew these were not there prior to the Windows 10 download.
I took good notes and when I referenced them I noted both of the 10 downloads came from the same server but the other 10 download did not. While I trust that MS has the servers doling out the Windows 10 upgrade are free of Malware and viruses but after this happening I wasn't so sure any longer. I played with each machine over the next several weeks and finally got them to where they were prior to trying the Windows 10 upgrade with the All in One Dell running like a champ the whole time I was at least becoming well versed with the in's and out's of Windows 10.
As a retired IM/IT Specialist working for Navy Medical prior to retiring I am a glutton for punishment. If you are having issues with your machine either running Windows 10 currently or are planning to upgrade to Windows 10 I encourage you to download and install the latest free version of Malwarebytes and run it. I always get downloads of this naturre from CNET as I have never had an issue with any software I've downloaded from their server. Then uninstall any A/V software you have, if you used Defender just disable it.
Even if you are not having issues with your Windows 7 with your Windows 7 disk run a repair and even something minuscule can cause a hiccup. Once this is completed install Windows 10, using this procedure got the 2 machines I thought I had brick running like champs. Don't forget to reinstall your A/V program or turn it back on in the case of Defender.
This may seem like a lot of work for an upgrade but considering the issues others have run into it's a walk in the park once you've done the upgrade and it works like it's supposed to, I find it the least memory hosed OS ever to come from Microsoft and fast like no tomorrow, it also got my hardware working the way it was intended. I hope this helps someone, regards.
banjo