The new Thermalright 120SE 7 heat pipe version is currently $39.99 shipped. Probably the better option if you only care about performance. The AK620 does look clean though if that's your thing.
Upgrade the RAM when you upgrade the CPU. No point in doing it now when the CPU doesn't have enough cores to handle any rendering that requires 64 GB of RAM....
Grab a cooler instead of an extra fan. The Thermalright PS120SE (RGB version here) is arguably the best air cooler on the market and is also a solid fit for the 13700 (get the non-K).
As far as switching CPUs, you would need to replace the motherboard also, as the risen will require an AM4 socket.
The Kraken M22 has been no end of problems to our clients over the last 30 months, as they seem not to age very gracefully. One of the larger issues is impeller failure, allowing the motor to spin but no water to flow positively..
As a rule of thumb, all of our clients with AIOs keep an air cooler under their desk, under their bed, in their closet, for testing and as a backup if they have to RMA their AIO.
Having one on hand, reduces problem solving down to nearly nothing, and headaches minimalized due to the reduction in downtime.
Also, our clients tend to service their AIO set up about every 12 to 14 months, making sure that they use a high performance thermal grease
And something better than canned air to clean out the coils
Some of our elderly clients figured this out, and they found a thousand different ways to use it.
But this is the best test procedure we come up with, that's relatively quick and easy.
MaxProAndU Team