First, do not stress yourself about the CPU temperature. Most modern CPU's are designed to operate up to 70 or 80C before they even start to throttle themselves to protect against overheating. I don't know the exact spec for your CPU chip, but you should be able to find that out by searching the net for specs for exactly your CPU chip.
Now, back to your dilemma. You have different results displayed to you from two different third-party utilities. As a general rule, many of these tools are NOT correct when you first get them, and they need some form of calibration to be sure they tell you the truth. One or both of them could be wrong. And as you have seen, for each one you need to do some detective work to determine which item is "Temp1", etc.
So what CAN you rely on? You have two different tools already supplied with your mobo by its maker. In BIOS Setup you can see and adjust the settings for each mobo fan header, and that includes the temperatures of the CPU internal sensor and of the mobo sensor. Those will be accurate. The problem is you cannot see those when you are actually using your system. So the second tool is a utility on the CD that came with your mobo. There will be some software tool there that should be installed on your system - may already have been installed when you installed all the mobo device drivers. Look in the folder of utilities named for your mobo maker. It may even have placed a small icon for that in your tray at bottom right of the screen. This tool usually has lots of items including ways to observe temperatures and fan speeds, and make adjustment to them if you wish. This tool is a Windows app and can be run and displayed on your screen during normal use, so you CAN observe while you are really using your system. Because it is already customized for your mobo by its maker, you can rely on its info.
Because you have an AIO system, there are a couple points you should check and get right. These include where you have things plugged in. All mobo fan headers do three functions, really. The provide power to the fan. The provide control of the fan speed that depends on the temperature actually measured by a relevant sensor, so they monitor that sensor to do this. They also monitor the fan speed signal, NOT because they need that to control speed (they don't) but to watch for FAILURE of the fan. On many mobos the monitoring for failure is given special emphasis by the CPU_FAN header, since failure of CPU cooling could be disastrous. Some mobos that have special headers designated for the pump unit of an AIO system also will give special attention to that component. For those reasons, where you plug things in is important. But also, for your own use, you need to know what is plugged into which header in order to understand what the mobo maker's monitoring software tool tells you.
The DeepCool Captain 120 EX system depends on your mobo's normal automatic fan control system to control cooling of the CPU chip. But it has TWO things to plug into separate headers - a pump and a rad fan. Like most such systems, it is designed to have the pump run full speed all the time, so its speed does not need control, but it DOES need failure monitoring. All control of the CPU internal temperature (the CPU has its own sensor built into and used by the mobo) is done by varying the speed of the rad fan.
You have not told us what mobo you have, so some of this will depend on what yours has. IF you have any special PUMP header (AIO_PUMP, SYS_FAN/PUMP, etc.), plug the PUMP unit into that header. In some cases you may need to specify in BIOS Setup that you want this header used for a pump. Then plug the rad fan into the CPU_FAN header. Both of these headers should use the CPU internal temperature sensor, and often you do not have any choice to make on that point.
If you have no special pump header but do have both a CPU_FAN and a CPU_OPT header, use those two. I suggest putting the PUMP on the CPU_FAN header and the rad fan on the CPU_OPT header. That is because I am sure the extra attention on possible failure WILL be done by the CPU_FAN header, and it should monitor the pump as the more important of those two. Again, both of these headers should be using the CPU temp sensor, but you may not have any option on that.
If you have only one CPU_FAN header plus some SYS_FAN or CHA_FAN headers, plug the PUMP into the CPU_FAN header so it can be closely monitored for failure. Plug the rad fan into a SYS_FAN or CHA_FAN header. For that one, look in its configuration options and try to find a place to specify whether it uses the CPU temp sensor or the one on the mobo, and set it to use the CPU sensor. If that is NOT available as an option, post back here the details of which mobo you have for a better way to do this. The rad fan speed really should be guided by the CPU internal temp sensor.