DevBiker

You can use an internal USB hub as long as it is independently powered. Do not use a USB hub that doesn't require some kind of connection (usually SATA these days) to the power supply. Corsair makes one here: https://www.corsair.com/us/en/p/pc-components-accessories/cc-9310002-ww/corsair-internal-4-port-usb-2-hub and I can confirm that it works just fine and dandy with a Commander Core, a Commander Pro and a Lighting Node Pro all connected at the same time. There are others that work as well. The key thing is that they need to be powered.

After messing around with my MM700, try this ... Remove the USB cable from the back of the hub. While holding down the button on the back of the MM700 hub, reconnect the USB cable. If that doesn't work, do it one more time.

It sounds like you are stuck in firmware update mode. Getting out of it is going to be some secret combination of connecting the device and holding down the button. Contact Corsair support ... I'm sure they'll know.

An EATX board is absolutely, positively, not a problem at all in the 7000. See

You can change the scale. Again, without knowing your ambient, it's hard to say - the ambient (room) temperature is going to be your baseline as that is the lowest possible temperature for the coolant. If your room temp is, say, 15C, that's not good. If its, say, 25C, its just fine and about the best you'll get while running. There are a couple of methods for installing the cooler. The best - from a cooling perspective - is for it to draw air in directly from the outside over the radiator (intake). However, the most common installation for a top-mounted radiator is to have it as exhaust. This isn't a bad thing but you do need to keep in mind that you'll have some element of internal waste heat going through the radiator. You can counter that with the intake/airflow fans in the case. You can set those to be controlled by the coolant temp or - even better - use the temp sensor in the exhaust flow of the rear/exhaust fan and base their speeds on the case's internal temperature. From there, you can adjust fan curves based on your personal preference for noise vs cooling. Higher fan speeds will cool better ... and also be louder. The default "Quiet" curve, as the name implies, leans more to quiet and will let the coolant get warmer than, say, Balanced or Extreme/Performance before it kicks up fan speeds. But you can create your own curves that are more attuned to your preferences and, more importantly, your environment. The AIO Pump header is simply a standard header set to 100%. It has absolutely no meaning outside being marketing fluff ... and most of them are 4 pin. But 3-pin and 4-pin fan headers are completely compatible with each other. Is it required to be on the CPU header? Only if you want to eliminate that warning. That warning can also serve as an early warning for pump failure.

Those coolant temps look fine (though it does depend on ambient). What are you expecting to see? A few details about the ambient temp and the installation would help. One thing to watch out for is exhausting GPU heat through the radiator or blocking airflow with glass. But since we don't know how you have it installed, it's impossible to provide any more detail. You should plug the CPU fan cable into the CPU Fan port, as indicated in the manual. It's not necessary for the pump to operate but it does provide a tach signal to the motherboard so you don't get a CPU Fan speed warning. Which explains exactly why you got that warning.

Why do you think it's not the correct PSU?

That's really up to you. Personally, I don't see the performance shown there being all that incredibly different and I (again, personally) find the Link system to be well worth it. Cable management is just so much easier. Well, the Commander Core's cable has such a 'splitter' already built in. Will it work? It depends on which of the 2 ports on the USB header the other device is using. Sometimes it'll work, sometimes not. It will work with the LCD. Yes, you'd need 3 USB ports. And yes, a powered hub will work. Corsair has a version as well - https://www.amazon.com/Corsair-Internal-4-Port-USB-2-0/dp/B0BGWPP23D/. I've used both and, IMHO, the arrangement of the ports on the Corsair hub is better arranged and easier to work with.

Look here: https://www.corsair.com/us/en/s/legacy-psu-cable-compatibility That PSU should be under the AX (Platinum) column so the EPS cable is the typical Corsair Type 3. The 24-pin ATX, however, appears to be different.

Are you running any other monitoring tools? HWInfo or anything like that?

Always check here: https://www.corsair.com/us/en/s/psu-cable-compatibility. As long as you stick to that, you'll be good.

I think that's going the be an RMA.

Put simply, your radiators should be all intake ... or all exhaust. As @c-attack said, having a radiator's exhaust as the intake to another radiator isn't a good idea. You lose efficiency in the loop. You could also flip them to all intake and just crank up the exhaust. The downside to this is that you have warmer air over the components. But it's still air movement and still keeps things within spec. On my 7000 build, I have 2 420mm radiators on intake, 4 120mm fans on the side with additional intake and a single 140mm fan for exhaust. The side intake helps cool the waste heat from the radiators. For control, I use the coolant temp to control the radiator fans and the exhaust fan temp (QX fan) to control the airflow fans in the side and rear.

Wow. That's good to know and watch out for. One would think it'd also have a way to prevent it from disabling certain background processes but fully disabling that certainly works. Add antiviruses to the list of things that can interfere with expected iCUE behavior ...

Profiles are in %AppData%\Roaming\Corsair\CUE5. By default, this is C:\Users\[UserName]\AppData\Roaming\Corsair\CUE5. But typing "%AppData%" in the Start ... Run dialog will get you there. You can then zip up the CUE5 folder; that's your full backup. Restore the folder to get it all back. You will need to have iCUE completely shut down when you do this.