Case for old desktop-gaming PC into new HTPC/couch-gaming PC.

[MrWizard6600]

Alright, hardware problems, please help:

Problems:

• old computer; see https://hardforum.com/threads/what-do-i-do-with-my-old-gaming-pc.2031134
• My reservoir is cracked
• My pump is too loud
• My radiator is an old 360mm rad
• I'm an idiot and I through out my stock air cooling stuff

I want:

• an HTPC form factor; reasonably sized (fits in my ikea media shelf, < 55cm wide by < 25cm tall by < 40cm deep)
• something quiet; my current swiftech dual pump thing is too loud.
• to spend less than $500 CAD (~$400 USD)
• a graphics card that will run Diablo 4 on SteamOS decently

so the poll is:

Solution 1: Air cooling, new GPU; purchase a new GPU and an air cooler for existing CPU.
Solution 2: Air cooling, existing GPU; purchase a "for parts" radeon RX 5700 XT, cannabilize its cooler, buy a new air cooler for existing CPU
Solution 3: existing liquid cooling; buy a new pump and reservoir, and **a case I know in that i put in the comments**
Solution 4: new 240mm radiator, pump, reservoir, and one of the HTPC cases that will fit it