Sorry was out walking dog.
System isn't too bad and I think you did the right thing getting one - wont get that much grunt for the money for a good while.
CPU and RAM speed may let you down a bit. PSU is fine - though is SF Small form? And case says mini - looks like it will fit if can do 360mm rads.
Hopefully it'll fit but seeing as you got such a great GPU that will do 4k currently in 95% of games, let alone 1440p @ 120hz - what you've saved on GPU for the money, will allow you to upgrade the rest. No harm in trying it - if your GPU usage in afterburner isn't in the 90%'s then the rest of your system is holding it up. Fastest RAM & Processor available 2nd hand for that 10yr old platform may get some extra legs in it - otherwise complete platform upgrade. AMD 3600X CPU will probabaly do it fine on AM4 platform.
1440p also - if you still have a 60hz monitor then it wont use the GPU fully either - hopefully you have a high hz monitor also. Old system and modern card - but you can upgrade the rest over time.
Maybe ask the question in the 6900XT owners thread.
Wive's? Just dont tell 'em if you can keep the case.