Replacing Razer Core X stock fans with Noctua for silent(er) operation
Hi everyone! I just wanted to share the results of an experiment I've done trying to reduce the noise of the Razer Core X enclosure by replacing them with Noctua fans.
The choice I made was NF-S12A FLX for 120mm case fan and NF-8A FLX for the PSU fan, both in 3-pin connector variant. The issues you may run into by doing this replacement are described very well in the r/eGPU post https://www.reddit.com/r/eGPU/comments/9qsgsh/upgrading_egpu_cooling_fans_razer_core_x/ .
Briefly, the main problem is with the PSU fan connector which is a 2-pin connector, and the author of the reddit post proposes the solution of soldering the fan wires to the PSU PCB for obtaining a constant 12V power supply for the fan, which scared be a bit but I was almost doing it.
Opening the Core X I noticed a connector on the GPU (Sapphire Vega 64 Nitro+) and I remembered that the graphics card user's guide indicates that connector as a case fan connector controlled by the graphics card for optimal air flow. I used that connector for the 120mm Noctua fan which freed the 3-pin connector on the Core X "motherboard". So I connected the PSU fan to the motherboard connector. And that was it. The change was not completely smooth, because initially I used the Noctua provided Low-Noise adapter NA-RC10 to extend the PSU fan cable to reach the motherboard connector, but the PSU fan did not spin. As a last try, I replaced the Low-Noise adapter (whatever purpose it may have) with the Extension Cable also provided in the Noctua box, and now the PSU fan spins. So far so good. I will keep you posted if I notice something weird in the next days.
Please be aware, that by doing this change, the PSU fan will not be controlled by the PSU itself. The reddit approach is providing full speed to the fan by using the 12V power (the fan is controlled by voltage, so 12V means maximum power). In my approach, the PSU fan is controlled by the Core X motherboard, which may lead to a full stop if the load is very low; I'm not entirely sure that this will not damage the PSU on a long run. So far, I did not notice a drop in temperature (the temperature reported by MONIT in MacOS is still around 74C under load) but at least the operation is a lot more silent.
I have the same setup, Razer Core X and Vega 64 Nitro but mine is the limited edition with 3 x 8 pin so I used an external PSU. I replaced the case fan with a noctua one with 4 pin pwm and connected it to the GPU. From my observation, the fan will be on all the time but at lowest speed so there is no noise at all. This characteristic may be useful if you want a constant airflow for PSU in your case.
The GPU doesn't really change the fan speed at all which is weird but when my laptop goes to sleep that fan will lost PWM signal and therefore spin at max speed.
I monitored the system for a while (low/high load, sleep, recovering from sleep, idling, etc).
Having the PSU fan connected to the Core X motherboard fan connector leads to complete PSU fan shut down when the system is idle or sleeping (in the same situations, the 3 fans of the Sapphire Vega 64 Nitro are also shut down) but the case fan I connected to the video card extra fan connector is still spinning no matter the system mode. I remind you that the case fan I'm using is a 3-pin model and the video card connector is a 4-pin connector so I assume the PWM control is disabled, so that's why the fan still spins when system is idle.
So I switched the fans again: the 120mm case fan goes to the normal 3-pin connector on the Core X motherboard (as it should be) and I connected the PSU fan (also 3-pin) to the video card connector.
Now, the PSU fan spins all the time which I think is better. I also must say that initially I was using a low-noise connector also for the case fan. Meanwhile, I did my homework, and apparently The Noctua Low-Noise connectors are just attenuators that basically make your fan spin at a lower speed (to reduce noise), which you may not want (especially with Vega 64 which heats a lot).
The results of the modified configuration (PSU fan spinning all the time and NO low-noise connectors) the graphics card seems to stay around 69-70C instead of initial 74C. Which looks better to me. I can still see a problem: the PSU fan does not spin at higher speeds if the system gets heated up. I can't remember how it was before, but I notice that Core X is warmer at the back (where the PSU is). I don't think I will keep this configuration for too long, just to avoid any heat generated problems to the PSU, so I think I will eventually switch the PSU itself.
Personally I think modern PSU will be fine as long as there is some airflow unless it is under constant heavy load. If you want better cooling for both GPU and PSU, you can replace the front fascia with a 140mm fan with no modification at all. Also replace thermal paste on the GPU may greatly improve your temperature. I don't remember the numbers off my head but I think your temperature is on the higher side.