Is there any value to a passive radiator?

[hef]

I'm digging into building an SFF system in an ITX case, specifically the Jonsbo A4. I bought this on a whim at auction as it was going cheap and I'd been considering moving to ITX anyway so I figured, why not?

Anyway, the case has a built in mounting position for a 240mm radiator at the top, 58mm clearance above the central spine so ideal for a 30mm thick rad and 2x standard 120mm fans - all good there.

The airflow of the case is vertical, bottom to top, with 2x 120mm inlets at the bottom, however the bottom inlet spacing is non-standardised so it's not directly compatible with mounting a second rad in the bottom but it shouldn't preclude there from being a second 240mm radiator bodged in there.
The real difficulty though is clearance as there is only 30mm available below the spine of the case, meaning it's gonna be a hella tight fit to get an actively cooled radiator of any kind in there....

I think I found a combo that may work involving a 17mm thick radiator and some 13mm thick Raijintek fans involving many weeks of shipping from the far east however I'm starting to wonder if it would be easier and not completely ineffective to just bash in another good quality "on-brand" 30mm radiator without any fans....?

Which approach is likely to be most effective and most worthwhile? Is it better to have a low quality actively cooled radiator or a high quality passive one?

FYI - The system will be cooling a 8700k and an RTX 3080 (if I can ever actually source one) so two 240mm radiators would be beneficial for sure.

 

[Hewligan]

I would think bringing cool air in from the bottom that is then exhausted through a radiator at the top is better than only having an exhaust setup and a passive on the bottom. I would expect the passive bottom radiator will slowly just heat up and trap warm air in the case.

I had (still have but now just an empty shell) and Alienware case earlier this year that I totally hacked to fit 2 x 240mm rads and fans. I managed to fit intake fans into a bottom rad, but the air intake was restricted and the internal case airflow was horrific. What I found was pretty poor cooling temps (like delta 20) as there wasn’t enough pass through of cool air.

But, the very best option (except for your wallet) is to try both!!!!

 

[Radox-0]

Overall I think on balance the radiator + thin fan combo will work better. When water temp gets warm, which it will in that case, even a little bit of airflow will help vs a slightly thicker passive radiator in my experience. Also the 17mm radiator, if its the same one from single link I have seen does a decent job: https://www.reddit.com/r/FormD/comments/ifjgrl/the_17mm_thin_radiator_is_actually_doing_ok/ Slight meh point is it does seem some people had leaks, but this was a while back so hopefully improved. So yeah I think 17mm combo with fans will win out over a passive one in terms of helping with temps, though overall may not be a massive delta.

Recommend when you do get a 3080 to look into undervolting, will lose couple of % performance, but power saving at say 0.85v will be pretty nice in most tittles (some will still demand more power like RT CP2077).