It's this one. Things concerning me is the two devices have 12 old years from each other 😅 
Discussion
Seems to be this one : Intel Core i7-3615QM @ 2.30GHz
https://www.cpubenchmark.net/cpu.php?cpu=Intel+Core+i7-3615QM+%40+2.30GHz&id=893
You can check tom’s hardware for cpu benchmark tests
TRIGKEY Desktop Computer Ryzen 5 5560U(6 Cores, 12 Threads) 16GB DDR4 500GB M.2 NVME(Max 2350MB/S) if can get 200€ - amazon . com/ryzen-mini-pc/s?k=ryzen+mini
289€ 😅
And I need 1TB for the BTC blockchain. Would be even better with a 2TB as I want it to be a BTC node for the next 5 years minimum. So your remark about adding a new SSD is a fair point. But it's also possible on the iMac apparently : https://m.youtube.com/watch?v=KlR-RWtqzis
future expansion is important