ChristianVirtual wrote:You might need to shutdown both systems when you want to work on only one. 19” rack for me next time ...

Shutting the rigs down is one thing. Having to tip one half completely upside down to properly work on the other side is the real risk, especially if you have both systems plumbed with multiple/heavy full-cover GPU blocks. The horrendously antiquated ATX 2.x spec was never designed around having 8Kg of high-performance GPU horsepower hanging sideways off a vertical motherboard, let alone suspended upside down by it's brackets

That's one thing I like about proprietary server stuff - they give ATX the finger
Now the creative modder in me could bolt two Case Labs frames together and use custom front/top panels, but that's a whole other discussion.
The CHALLENGE with server stuff is integrating water cooling, since airflow in a rack is not multi directional and big radiators eat away density. For me the benefits of a custom loop (quiet fan noise, choice in cooling radiator capacity, lower temps and the ability to run during high summer ambients) are significant, and done right, allow me to run 24/7 with an expected hardware lifetime of 5 years before looking at any platform upgrade. My only maintenance is draining and flushing the loop every 12-18 months and dusting off the filters.
Trying not to get too off topic, but maybe you can tell I am really into high-end stuff like this
