It is probably not the best idea to use CPU_FAN_OPT for anything other than CPU fan…

Take this with massive NaCl crystals… as I am definitely not an expert in this area, but… I believe I *might have resolved some odd issues my AMD Wraith prism (which came with the Ryzen 7 2700X)was running into.

I put this computer together about last Prime day, and worked reasonably well… except sometimes, suddenly, all/many/some fans stops working. As in, completely, shut off.

Other times, I left the computer on for sometimes and come back to find the computer turned off by itself. After using the computer for a while, I personally observed several times where the CPU fan STOPPED working while I am in the middle of things, not necessarily computationally intensive stuff either. It was super weird. I was suspecting a faulty Wraith Prism… but come on, a brand new fens, how complicated it can be. Then, it happened several time where thermal shutdown actually happens due to excessive heat from the CPU (i.e. thermal protection kicked in to force shutdown)…. No doubt that shortened my CPU life by quite a few cycles..

Another thing I observe was that… my CPU was running hotter than probably most other 2700X reported. I am at around 55+ to sometimes 65+. Some say it is normal but I figure, it is probably a overclocked chip so it should run hotter than that… Big deal…

Then, today, I finally had enough and decided to see what is up. My motherboard is ROG Crosshair VI Extreme (a pretty old mobo). The CPU fan (wraith prism) is plugged into the CPU_FAN slot as intended… so nothing super unusual. Then, I saw I plugged a case fan extension card into the CPU_FAN_OPT card slot. Normally, I figure that an additional extension card on a regular fan out slot cannot be that bad… so I decide to move the card off from the CPU_FAN_OUT from there to a radiator/fan header instead.

Then when I put the computer back together, instantly, I am seeing my 2700X chilling at around 38C instead of the regular 50/60+. BAM. ten degree deduction at least. Also noticeably, the fan is spinning faster as well (normally, I can see the individual fan leaf)… So while correlation doesn’t not imply causation, I am happy with the current configuration and will DEFINITELY avoid plugging anything into the CPU_FAN_OPT unless it is actually another CPU related fan…

My suspicion is that maybe the CPU_FAN_OPT and CPU_FAN are working in conjunction and when one is drawing too much power, the other might have reduced current/voltage. If my other case fan are spinning hard, it might reach low enough current to the main wraith prism to cause it to stop. I can probably run another experiment to see but I am quite lazy and so far very happy with the way this is turning out… and hopefully better service time of my computer… I will update should I run into the shut off issue further down the road.