[SOLVED] Installation of water cooler

Jan 11, 2019
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Hey wonderful folks.

I'm about to install my water cooler into my pc. What I'm unsure about is whether the fan or the pump should be connected to the CPU Fan 4 pin slot on my motherboard. I'm a little confused about this one since I've seen different responses and answers in my searches online. Which configuration would be the best, if any? Would one be beneficial over the other or are there no difference at all? Both the pump and fan has 3-pin headers, if that helps.

Thank youadvance. :)
 
Thanks for that info. It settles several questions and provides a final answer.

Your mobo has only one CPU_FAN header, plus two CHA_FAN headers. In the manual there is no indication that either of the CHA_FAN headers can offer choices about which temp sensor to use, so you can use only the CPU_FAN header for controls based in the internal CPU chip temperature. This produces a small dilemma, too. You will need to have both the pump and the rad fan connected to this header. The pump needs to be there so it can be monitored closely for failure. The rad fan needs to be there also so that it can be controlled by the CPU chip internal temperature. But that means that the fan can NOT be monitored for failure because only the pump speed signal can be sent back to this header. So over the long term, you will need to remember to check from time to time that the rad fan is working.

Another issue rises from the mobo info. The manual indicates that all of its fan headers use the new PWM Mode of control with no option for the older DC Mode. That means that none of these headers can control the speed of the 3-pin fan that came with your Asetek 510. (This is not an issue for the pump since it should operate at full speed all the time anyway.) I suggest your best choice here is to buy a different fan to use on the radiator. Get a 120 mm size fan of the new 4-pin (PWM type) design, the speed of which the header CAN control. Chose one that is specified to be optimized for "high pressure" (not max air flow), since this will be pushing air through the small spaces between fins of the radiator. In choosing, do not look too closely at the speed of the fan. You want one that has higher air flow but certainly has a higher pressure spec. "Pressure" specs typically are in mm of water, and values of 1 to 2 are low, typical of "air flow" optimized units. Pressure specs for rad fans should be over 2.5 mm, may be up to 4 mm or even above that for some. So look first for the pressure specs, then among those that qualify look at the air flow rating. And lastly, look at the noise value in dBA - less is better.

Once you get that replacement fan, you need a way to connect both the rad fan and the pump together to the CPU_FAN header. For that you need a simple SPLITTER. Here's an example of one that looks like just cable "arms". It is a 4-pin model, but it will work well with both 3- and 4-pin fans and your pump.

https://www.newegg.com/p/N82E16812423161?Description=coboc fan splitter&cm_re=coboc_fan_splitter-_-12-423-161-_-Product

That one has 12" long "arms", but a 6" one also is available. Note that this SPLITTER has only two types or "arms". One ends in a female (with 4 holes) connector that plugs into your CPU_FAN header. The other arms both end in male outputs for the pump and a fan. Do NOT buy a HUB; it is a different device that has an additional"arm" that must plug into a SATA or 4-pin Molex power output from the PSU, and you do not need that.

Look closely at the two outputs. ONE of them has all 4 pins, and that is the one that WILL return the speed signal from its device to the header. So plug in your 3-pin PUMP connector there. The other is missing Pin #3, which is how it avoids sending the speed signal from that device to the header. Plug your 4-pin fan in there. That may seem backwards, but that is the right way. This will allow the CPU_FAN header to change the fan's speed according to the CPU internal temperature, but the fan's actual speed will never be "seen" by the mobo. Meanwhile, the way the pump wiring is designed, it will always receive the full 12 VDC power it needs. For most pumps, that means it would run full speed all the time; however, as I said above the Asetek web page indicates it may change its own speed independent of the mobo header. With connections made this way, the mobo CPU_FAN header WILL show you the speed of the PUMP unit, and will monitor it for failure.
 
Unfortunately I could not find any instructions for installation of the Asetek 510LC system. So all I can do is recommend on general principles.

Most AIO systems are designed so that the PUMP operates at full speed all the time and requires NO speed control. ALL of the control of CPU cooling is done by altering the speed of the RAD FAN, so that fan does need mobo-based automatic speed control that is guided by the temperature sensor inside the CPU chip. That sensor is always used by the CPU_FAN header, and usually also by any auxiliary CPU headers such as CPU_OPT, etc. SOME mobos also allow you to configure a CHA_FAN or SYS_FAN header to use the CPU chip's temp sensor instead of the motherboard sensor.

A fan header has TWO functions. The first is to alter the fan speed in response to the actual temperature measured on the "hot spot" (the CPU chip or the motherboard) that the fan is cooling. But also important is the secondary function of monitoring the fan for FAILURE, interpreted as a fan speed reading that is zero or less than some specified minimum. Now, when it comes to AIO systems, you have TWO components to monitor for failure - the pump and the rad fan. On many mobos the CPU_FAN header (and often a few others such as CPU_OPT and PUMP headers), the failure monitoring system takes quick action if failure is detected. It certainly will send out a warning message on-screen. But it may also initiate a complete system shut-down without even waiting for the CPU's internal temp sensor to report excessive high temps. Some even refuse to let you start up if there is NOT fan speed signal getting to the CPU_FAN header. This is all to ensure that the CPU never overheats so badly and quickly that it is damaged.

Given those points, my preference IF you can is always to connect the PUMP to the CPU_FAN header because failure of that item WILL cause failed CPU cooling and rapid temperature rise. Failure of the rad fan, on the other hand, will cause a slower temp rise inside the CPU because some of the heat still is being carried away to the rad. However, that also depends on whether you do have a good way to control the rad fan speed.

And here's another fine technical detail. Any 3-pin fan connected to a mobo fan header that actually is using the new PWM Mode of control for 4-pin fans will always run full speed. So, many AIO system makers supply their PUMP wired just like a 3-pin fan and expect you to ensure that the CPU_FAN header you plug it into (or other header) IS configured to use PWM Mode. That way the pump does actually run full speed all the time, as intended. PLUS, if you plug the PUMP into the CPU_FAN header, its speed is monitored properly for failure. m(Actually, I note on the Asetek web page for this cooler that it claims the pump unit does its own speed adjustments internally (does NOT use the mobo header speed controls) based on its own sensor of the temperature of the circulating liquid. That is an unusual design!) But then you still need some fan header that uses the internal CPU chip temp sensor to guide it so you can plug the rad FAN in there and control its speed (and hence the CPU cooling) that way. If you have a CPU_OPT header, that is ideal for that. Alternatively, if you have a CHA_FAN or SYS_FAN header that allows you to use the CPU's internal temp sensor to guide it, that also can do well for the rad fan.

OP, you say the system you have has 3-pin connectors on the wires from BOTH the pump and the rad fan. That makes it a bit tricky because the 3-pin fan MUST have its control done using the older Voltage Control Mode (aka DC Mode), and that must be done by a header that can use the CPU temp sensor. BUT you do not want the PUMP to be fed from a header that uses that Mode, because its voltage should NOT be reduced at low CPU temps. So you need separate headers for those two items, and it is desirable that the PUMP at least (and preferably also the rad fan) be monitored closely for FAILURE just as a CPU_FAN header would do. To be sure we give you the best advice, post back here the maker and exact model number of your mobo so we can examine the details of how its fan headers operate.
 
Reactions: koltzebenjamin12
Thanks for that info. It settles several questions and provides a final answer.

Your mobo has only one CPU_FAN header, plus two CHA_FAN headers. In the manual there is no indication that either of the CHA_FAN headers can offer choices about which temp sensor to use, so you can use only the CPU_FAN header for controls based in the internal CPU chip temperature. This produces a small dilemma, too. You will need to have both the pump and the rad fan connected to this header. The pump needs to be there so it can be monitored closely for failure. The rad fan needs to be there also so that it can be controlled by the CPU chip internal temperature. But that means that the fan can NOT be monitored for failure because only the pump speed signal can be sent back to this header. So over the long term, you will need to remember to check from time to time that the rad fan is working.

Another issue rises from the mobo info. The manual indicates that all of its fan headers use the new PWM Mode of control with no option for the older DC Mode. That means that none of these headers can control the speed of the 3-pin fan that came with your Asetek 510. (This is not an issue for the pump since it should operate at full speed all the time anyway.) I suggest your best choice here is to buy a different fan to use on the radiator. Get a 120 mm size fan of the new 4-pin (PWM type) design, the speed of which the header CAN control. Chose one that is specified to be optimized for "high pressure" (not max air flow), since this will be pushing air through the small spaces between fins of the radiator. In choosing, do not look too closely at the speed of the fan. You want one that has higher air flow but certainly has a higher pressure spec. "Pressure" specs typically are in mm of water, and values of 1 to 2 are low, typical of "air flow" optimized units. Pressure specs for rad fans should be over 2.5 mm, may be up to 4 mm or even above that for some. So look first for the pressure specs, then among those that qualify look at the air flow rating. And lastly, look at the noise value in dBA - less is better.

Once you get that replacement fan, you need a way to connect both the rad fan and the pump together to the CPU_FAN header. For that you need a simple SPLITTER. Here's an example of one that looks like just cable "arms". It is a 4-pin model, but it will work well with both 3- and 4-pin fans and your pump.

https://www.newegg.com/p/N82E16812423161?Description=coboc fan splitter&cm_re=coboc_fan_splitter-_-12-423-161-_-Product

That one has 12" long "arms", but a 6" one also is available. Note that this SPLITTER has only two types or "arms". One ends in a female (with 4 holes) connector that plugs into your CPU_FAN header. The other arms both end in male outputs for the pump and a fan. Do NOT buy a HUB; it is a different device that has an additional"arm" that must plug into a SATA or 4-pin Molex power output from the PSU, and you do not need that.

Look closely at the two outputs. ONE of them has all 4 pins, and that is the one that WILL return the speed signal from its device to the header. So plug in your 3-pin PUMP connector there. The other is missing Pin #3, which is how it avoids sending the speed signal from that device to the header. Plug your 4-pin fan in there. That may seem backwards, but that is the right way. This will allow the CPU_FAN header to change the fan's speed according to the CPU internal temperature, but the fan's actual speed will never be "seen" by the mobo. Meanwhile, the way the pump wiring is designed, it will always receive the full 12 VDC power it needs. For most pumps, that means it would run full speed all the time; however, as I said above the Asetek web page indicates it may change its own speed independent of the mobo header. With connections made this way, the mobo CPU_FAN header WILL show you the speed of the PUMP unit, and will monitor it for failure.
 

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