New
#11
In the end, it all comes down to money. What is your budget?
Usually a new MB means new memory and CPU as well. If the old MB is bust, then I would buy a new MB, CPU and memory capable of running Windows 11 within your budget. Do you have a Windows 10 retail licence? If not, a new MB & CPU might require a new Windows licence, but these can be found quite cheaply.
I would only buy a MB from Asus or Gigabyte which are more reliable and have good warranties and support.
And?
UserBenchmark: Intel Core i5-11600K vs i5-8400
My point is that if you have to replace the motherboard, you may as well go for a CPU that is more up-to-date. The I5-8400 is a discontinued product. It may be more expensive than a newer CPU.
Used is a different story. But if the OP is considering used components, it may make more sense to buy a whole used PC.
The motherboard and cpu are the 2 most important parts of your build to start out with, get the best you can afford
If you buy a new i7 CPU, 8G memory and MB it will cost more than US$550 (340+70+ 140).
As OP said, he doesn't need a cutting edge system and he already has a good CPU
ebay - Z97 MB
Just a comment, because I visit clients in their location I'll be getting a new Notebook first then later a new Desktop or components. The reason for the Notebook first is to answer questions and show what Win11 is about for those clients when asked. For most of them I'll stress the 4 years their equipment still has, budget issues.
What you're going to do with Win 11 that you don't do with Win 10? Nothing!!!!
Why worry with a OS that hasn't been released?
At the win 10 end of support there will be a much better hardware. Then you should think about a new hardware.