Best case fan adapter? CPU fan question

I'd consider just buying molex powered fans & manually downvolting them to 7v, or buying a twin or triple 7v converter cable.
Its the cheaper option & still offers decent rests.

Failing that if you'd rather go the fan controller route, assuming you haven't filled both your 5.25 inch bays.

https://www.amazon.com/gp/aw/d/B00V80IQTS/ref=mp_s_a_1_1?ie=UTF8&qid=1483948984&sr=8-1&pi=AC_SX236_SY340_FMwebp_QL65&keywords=fan+controller+bay&dpPl=1&dpID=41J4Es4Yp8L&ref=plSrch

CPU coolers ??

You pay more for lp type ones, I'd honestly recommend the gammaxx 300 if you're prepared to go with a smaller tower cooler.

https://www.amazon.com/gp/aw/d/B007JEMX4Q/ref=mp_s_a_1_1?ie=UTF8&qid=1483949244&sr=8-1&pi=AC_SX236_SY340_FMwebp_QL65&keywords=deepcool+300&dpPl=1&dpID=41dIAL0S2fL&ref=plSrch

Its a novice fit cooler (takes 2 minutes) & a goid choice.

if they are PWM, yes.

Unfortunately, your choice of those fans means you are trying to power and control 3-pin fans from a 4-pin system on the mobo ports. That does not work. Any 3-pin fan on a true 4-pin port (one that uses PWM Mode, as your does) can only run full speed. However, there is a way to do this if you stick with 3-pin fans.

But and install this particular fan HUB: the Phanteks PWM Hub. Like most fan Hubs, this unit has one cable arm that plugs into a mobo 4-pin fan header that MUST be using PWM Mode, which yours does. With that connection it gets the PWM control signal it needs and returns to the mobo only ONE of its fan's speed signals - the fan plugged into the Hub's white Port #1. Then it has another cable arm that plugs into a SATA power output connector from the PSU, and this is where all the power for the fans comes from, thus avoiding the limited capacity of the mobo port itself. But this Hub is unique among others because it does not merely share that PWM signal to it fans. Instead it uses it to create its own group of six 3-pin ports operating in Voltage Control Mode, which is required for using 3-pin fans. (Because of backwards compatibility in 4-pin fan design, you also can control 4-pin fans from this type of port.) That gives you six ports for case fans. In fact, you can connect up to 2 fans PER PORT using simple splitters, and two of those are included with the Hub. One hint with this unit: change one detail of how it is connected. Its instructions tell you to plug it into only the mobo CPU_FAN header, and then plug your CPU cooler into the Hub's white POrt #1. Do not do this. That instruction is only to be SURE the Hub gets a PWM signal, but your mobo WILL provide that signal from the SYS_FAN header. So leave your CPU coller plugged into the mobo CPU_FAN header, and plug the Hub's fan connector arm into your working SYS_FAN header. Then just be sure that one of your case fans is plugged into the Hub';s white Port #1. This way all your case fans will be under automatic control by the mobo via the SYS_FAN header. Just one more caution. In BIOS Setup for this port, make sure it is Enabled and configured to use Standard Mode.

Now, IF you are willing to ensure that all your case ventilation fans are of the 4-pin design instead, then you can use a different and cheaper 4-pin fan Hub. This type of Hub only works when you connect it to a mobo header that uses PWM Mode (yours does) AND all your fans are 4-pin. It advantage for your situation is that it can handle many fans, and power for all of them comes from the Hub's connection to the PSU; no power is required from the mobo SYS_FAN header which is limited. Here's an example of one with five output arms:

http://www.newegg.com/Product/Product.aspx?Item=N82E16812423166&cm_re=Coboc_4-pin_splitter-_-12-423-166-_-Product

It connects to your PSU using a 4-pin Molex output connector. This unit is certainly cheaper than the Phanteks Hub, but it would force you to buy 4-pin fans, which may be more expensive. By the way, some places call this a "Splitter" because it is not a box with ports, but I call it a HUB because it does not merely split mobo signals to several fans. It actually gets power for the fans from the PSU, and only shares to its fans the PWM control signal.

You can get away with simple fan spliter. like this https://www.amazon.com/Splitter-Extension-Sleeving-Connectors-Length/dp/B00C46DX4S
i use those to connect my fans to MB headers. Since they are mounted on radiators, I do want them in duos.
that way i control every radiator
if you were to use Noctua fans, i'd say 3-4 fans per MB header are fine.
I don't know how much power those TT fans consume, but 2 is definitely good.

While I woudlnt generally have an issue with straight splitters the fact that 2 board headers have already failed would still lead me to push towards either downvolted molex fans or a proper controller.

If either of those 2 remaining baord headers fail for some reason you are just going to be downright stuck at the end of the day.

That controller you linked on newegg is the same one I linked anyway.
You can buy cheaper ones but the thermaltake is quality,will match your case, & has a decent warranty.