mingus wrote:probably stick with stock Mugen5 fans. Noctua's are great tho.
Its not as good as NF-A12x25, but i would use it, its pretty good. I also think its a good route to go with the same fan for the back case, instead of the Bequiet to save some money, while on 140mm its harder to get good fans, on 120mm there is a lot more options,
Scythe Kaze Flex 120mm Fan, Quiet Case/CPU Cooler Fan, 4-Pin 300-1200 RPM(SU1225FD12M-RHP) is what comes bundled on the Mugen5, ill try to explain down below why i suggested the Kazaflex over the Bequiet, for now i leave you the PWM graphs of the fans suggested.
Scythe Kaze Flex 120 PWM SU1225FD12M-RHP.jpg
be quiet! SILENTWINGS 3 PWM BL066 120mm 1450rpms.png
be quiet! SILENTWINGS 3 PWM BL067 140mm 1000rpms.png
mingus wrote:3 case fans, 3 headers, maybe one for the CPU fan, so splitter needed?
Yes and no, you will have 4 fans (3 case 1 CPU) and 3 headers, so in essence you do need one
PWM Y Splitter, i would use it for the two frontal Bequiet BL067, as both fans will be identical. I would then use one for the CPU fan and the remaining for the Back case fan, but i had one small issue during my build, for some reason that i couldn't drop the BL067 below 800rpms on one of the headers (i think was the CHA_FAN1), like the board was trying to undervolt it instead of using the PWM signal, not sure if its an issue just with my board, but i solved by changing to another header and the NF-A40 worked fine on the header that the BL067 didn't allow to be dropped below 800rpms. This is one of the main reasons im suggesting you also get a Kazeflex fan for the back, if you encounter the same issue as me, you can solve it with two
PWM Y splitters, one for the front and one for the CPU and back.
If you have time, do the following, lay down the motherboard over the carton box it come with, install the NVME, the 9700F, the Mugen5, connect the Kazaflex fan to the CPU_FAN header, connect the back case fan to the CHA_FAN2 header and BL067 to the CHA_FAN1, connect the PSU power cord, 8pin and 24pin to the motherboard and short with screw driver the power pins on the motherboard to start the pc, enter the bios and play with the fan curves, try to see if you can reach the values i posted on the graphs above, this is just to make sure you wont have the issue i had with BL067 and how you will connect them once you assemble on the case, this will save you a lot of time that i lost. If you dont have my issue, you can use all 3 headers, if you do, you can only use two headers, meaning that the back case fan would ideally be the same as the CPU fan so you know the same rpms are being ran when controlling it, and this is why the PWM splitters are useful.
mingus wrote:hopefully, I can dial all the fans in pretty well.
Its pretty easy, and its easier than it looks, enter the bios, go into the Hardware monitor and don't run the automatic tuner, i personally don't use use it but feel free to test it, but if you do, remove the delays it places on each fan. Check that each fan is set to CPU temperature (i don't use chipset to setup my fans, but up to you). Go Fantastic Tuning an setup each graph according to your personal preferences, Ill give you some starting points that are only suggestions into what will be quiet and still sustain the 9700f fine, but take them as references but you should be the final saying on here, maybe you like more quiet or more cool and willing to take more noise, etc, again here is up to you.
For the BL067 start between 30-40% PWM for 55C on temperature, the second breakpoint place 40-50% for 65-70C, the third breakpoint place 60% PWM for 80C, the 4th break point i would suggest 85C 90% and the fifth 100% 86C. If you see it starts very low and the slope of the graph is very mild, once it reaches above 70C climbs very fans, the idea here is to have a very quiet pc on idle, light load, even gaming, but if you go into encoding or editing and the CPU temp climbs to have a appropriate response from the fans. Space the first breakpoint on temperature, i chose 55C because thats the spikes it reaches sometimes opening programs, i try to cushion any normal load that i have on the first breakpoint, this helps to evade any breathing effect, like if you start too low on temperature with a very low PWM, you will have spikes that will start throwing the fan up and down a lot, and in some cases this is much more perceivable than a standard sustain rpm.
Asrock Bios fan curve.jpg
The the suggested graph as starting point, you should change it as you feel its better for you, there are some that even turn off fans and start them at certain temperatures, etc, remember after you setup the graph, enter windows do the usual things and even run some stress tests, so you get a feeling into if you need to change the graph, this process takes me about two hours of rebooting into the bios and doing small changes and re entering windows and testing, but once you do it well, its very likely you will never change it, and since its bios fan control its very reliable vs software, and you can down the road go into other OS like linux and still have the same settings as its OS independent.