Without a budget in mind, or if you’re using an AIO or an aircooler and at least your CPU and GPU, I can only give a glimpse of some scenarios. If going quantity over quality, fully populate all with P12s. Front and side intake, that’s 6 fans. No need to go over 800rpm for front and less rpm for side if using the “canopy”, as it would be very noise as is too close to the fans. I would say 500-600rpm max, just a breeze straight over the motherboard. Top and rear exhaust, slightly lower rpm than intake.
you can also use Thermalright TL-B12 (can be fount for £7.50-£8. Much better fan than the P12 for noise.
For RGB, the D30s are good but performance the T30 is king.
the only issue is that even if you are willing to shed £200+ in T30s, the only real benefit of such great fans is when the user needs more airflow but noise is a concern. They’ll outperform pretty much anything at the same noise level.
But there’s also noise profile to consider.
