[SOLVED] Fans and radiators.

Oct 23, 2020
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Hello,

if I buy 2 or more fans for the front of my PC case, is there a way to join them so I'm only using one fan slot on the Motherboard for the 2 fans?

Also, what is the difference between a fan and a radiator?

Thanks.
 

Paperdoc

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Ambassador
To cool a CPU chip, the most common is a combination of a heatsink and a fan. The heatsink is a shaped metal block with many fins that is clamped tightly to the top of the CPU chip, with a thin layer of thermally conductive paste between. Heat generated by the CPU flows into the heatsink. Then a fan attached to that blows air through the spaces between the fins to remove the heat from the heatsink metal into the case air.

A popular alternative that may be able to remove more heat (useful for high-power CPU's and heavy workloads) is some form of liquid-loop cooling system. There are custom assemble-yourself options here, but the most popular is an AIO (All-In-One) system with everything supplied and pre-assembled. In these, a single module that clamps onto the top of the CPU chip (with paste, too) contains a form of heatsink with no fins and a pump with hose connections. Those hoses are connected to a small radiator of tubes with fins that you mount on an outside opening of your case. Then fans are mounted on the radiator to blow air through the fins and remove heat. When running, the pump unit runs full speed all the time and continuously circulates a water-based fluid around the loop from pump to rad and back, thus moving heat from the CPU to the rad where the air flow from the fans can move the heat outside the case. (Well, in some installations the rad actually sucks cool outside air through the rad into the case, but it's the same result.) So an AIO liquid-cooler system is more complex, but may be able to remove heat faster than a heatsink and fan can do.

All mobos include at least two very similar but separate automatic fan control systems. These actually are TEMPERATURE control systems that concentrate on maintaining a TEMPERATURE at a specified sensor, and do that by manipulating the speed of a fan that removes heat with air. There is always one system that focuses on the temp of the CPU chip, and uses a temp sensor built into the chip by its maker. That system controls the fan speed signal of the CPU_FAN header. For a heatsink / fan cooling system, it simply controls that fan's speed. For an AIO system, commonly the design is that you connect the PUMP unit to a power supply that can provide a constant 12 VDC supply so it always runs full speed, and then the RAD FANS are powered from the CPU_FAN header and the CPU internal temp is controlled solely by the speed of the rad fans.

A second system uses a different temp sensor built into the mobo by its maker and that guides all the CHA_FAN or SYS_FAN headers. These fans are used for general case ventilation air flow and cool the entire system with emphasis on the temperature of mobo components. SOME systems offer the user options to change what temp sensor is used for these headers for special circumstances.

From an overall perspective, the main aim is to provide optimal AIR FLOW THROUGH the case, since flow rate determines heat removal rate. This means that a case should have similar air flow capability on BOTH intake and exhaust fans. What goes in MUST come out, so approximately equal assistance for air flow IN and air flow OUT is ideal.
 
Last edited:
Hello,

if I buy 2 or more fans for the front of my PC case, is there a way to join them so I'm only using one fan slot on the Motherboard for the 2 fans?

Also, what is the difference between a fan and a radiator?

Thanks.
Fan is the thingy like a propeller with blades turning and producing wind.
Radiator is thingy same but smaller than one in any car and certainly smaller than on bus, full with water and is to transfer heat energy from CPU to a better place.
Yes you can use a splitter (with right number of wires) to connect 2 fans together to one receptacle on the MB, they'll run at same speed as adjusted by BIOS.
 
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Paperdoc

Champion
Ambassador
To cool a CPU chip, the most common is a combination of a heatsink and a fan. The heatsink is a shaped metal block with many fins that is clamped tightly to the top of the CPU chip, with a thin layer of thermally conductive paste between. Heat generated by the CPU flows into the heatsink. Then a fan attached to that blows air through the spaces between the fins to remove the heat from the heatsink metal into the case air.

A popular alternative that may be able to remove more heat (useful for high-power CPU's and heavy workloads) is some form of liquid-loop cooling system. There are custom assemble-yourself options here, but the most popular is an AIO (All-In-One) system with everything supplied and pre-assembled. In these, a single module that clamps onto the top of the CPU chip (with paste, too) contains a form of heatsink with no fins and a pump with hose connections. Those hoses are connected to a small radiator of tubes with fins that you mount on an outside opening of your case. Then fans are mounted on the radiator to blow air through the fins and remove heat. When running, the pump unit runs full speed all the time and continuously circulates a water-based fluid around the loop from pump to rad and back, thus moving heat from the CPU to the rad where the air flow from the fans can move the heat outside the case. (Well, in some installations the rad actually sucks cool outside air through the rad into the case, but it's the same result.) So an AIO liquid-cooler system is more complex, but may be able to remove heat faster than a heatsink and fan can do.

All mobos include at least two very similar but separate automatic fan control systems. These actually are TEMPERATURE control systems that concentrate on maintaining a TEMPERATURE at a specified sensor, and do that by manipulating the speed of a fan that removes heat with air. There is always one system that focuses on the temp of the CPU chip, and uses a temp sensor built into the chip by its maker. That system controls the fan speed signal of the CPU_FAN header. For a heatsink / fan cooling system, it simply controls that fan's speed. For an AIO system, commonly the design is that you connect the PUMP unit to a power supply that can provide a constant 12 VDC supply so it always runs full speed, and then the RAD FANS are powered from the CPU_FAN header and the CPU internal temp is controlled solely by the speed of the rad fans.

A second system uses a different temp sensor built into the mobo by its maker and that guides all the CHA_FAN or SYS_FAN headers. These fans are used for general case ventilation air flow and cool the entire system with emphasis on the temperature of mobo components. SOME systems offer the user options to change what temp sensor is used for these headers for special circumstances.

From an overall perspective, the main aim is to provide optimal AIR FLOW THROUGH the case, since flow rate determines heat removal rate. This means that a case should have similar air flow capability on BOTH intake and exhaust fans. What goes in MUST come out, so approximately equal assistance for air flow IN and air flow OUT is ideal.
 
Last edited:
Oct 23, 2020
85
1
35
0
To cool a CPU chip, the most common is a combination of a heatsink and a fan. The heatsink is a shaped metal block with many fins that is clamped tightly to the top of the CPU chip, with a thin layer of thermally conductive paste between. Heat generated by the CPU flows into the heatsink. Then a fan attached to that blows air through the spaces between the fins to remove the heat from the heatsink metal into the case air.

A popular alternative that may be able to remove more heat (useful for high-power CPU's and heavy workloads) is some form of liquid-loop cooling system. There are custom assemble-yourself options here, but the most popular is an AIO (All-In-One) system with everything supplied and pre-assembled. In these, a single module that clamps onto the top of the CPU chip (with paste, too) contains a form of heatsink with no fins and a pump with hose connections. Those hoses are connected to a small radiator of tubes with fins that you mount on an outside opening of your case. Then fans are mounted on the radiator to blow air through the fins and remove heat. When running, the pump unit runs full speed all the time and continuously circulates a water-based fluid around the loop from pump to rad and back, thus moving heat from the CPU to the rad where the air flow from the fans can move the heat outside the case. (Well, in some installations the rad actually sucks cool outside air through the rad into the case, but it's the same result.) So an AIO liquid-cooler system is more complex, but may be able to remove heat faster than a heatsink and fan can do.

All mobos include at least two very similar but separate automatic fan control systems. These actually are TEMPERATURE control systems that concentrate on maintaining a TEMPERATURE at a specified sensor, and do that by manipulating the speed of a fan that removes heat with air. There is always one system that focuses on the temp of the CPU chip, and uses a temp sensor built into the chip by its maker. That system controls the fan speed signal of the CPU_FAN header. For a heatsink / fan cooling system, it simply controls that fan's speed. For an AIO system, commonly the design is that you connect the PUMP unit to a power supply that can provide a constant 12 VDC supply so it always runs full speed, and then the RAD FANS are powered from the CPU_FAN header and the CPU internal temp is controlled solely by the speed of the rad fans.

A second system uses a different temp sensor built into the mobo by its maker and that guides all the CHA_FAN or SYS_FAN headers. These fans are used for general case ventilation air flow and cool the entire system with emphasis on the temperature of mobo components. SOME systems offer the user options to change what temp sensor is used for these headers for special circumstances.

From an overall perspective, the main aim is to provide optimal AIR FLOW THROUGH the case, since flow rate determines heat removal rate. This means that a case should have similar air flow capability on BOTH intake and exhaust fans. What goes in MUST come out, so approximately equal assistance for air flow IN and air flow OUT is ideal.
Thank you very mush for your reply... and not a "thingy" in sight, hehe.

If I can, I will describe my setup for you and if you can, please advise of fan orientation, etc.


My case... https://www.pbtech.co.nz/product/CHAPHA6100/Phanteks-Enthoo-719-Black-Full-Tower-Case-Tempered

My Motherboard... https://www.pbtech.co.nz/product/MBDASU25715/ASUS-ROG-CROSSHAIR-VIII-HERO-WI-FI-X570-ATX-For-AM

My GPU... https://www.pbtech.co.nz/product/VGASAP16715/Sapphire-NITRO-Radeon-RX-6700-XT-Graphics-Card-12G


Air Out fans.

My CPU Cooler... (112 cubic m/hr)… https://www.pbtech.co.nz/product/FANCLM0215/Cooler-Master-Hyper-212-LED-Turbo-CPU-Cooler-RED-L?qr=related-view

My rear top out take fan, (right beside the CPU cooler).. (315 cubic m/hr)... https://www.computerlounge.co.nz/shop/components/cooling/fans/noctua-industrialppc-nf-a14-ippc-2000-pwm-140x140x25mm-4-pin-2000rpm-max-ip67-fan

=427 cubic m/hr air out.


Air in fans.

My front bottom intake fan... (315 cubic m/hr)... https://www.computerlounge.co.nz/shop/components/cooling/fans/noctua-industrialppc-nf-a14-ippc-2000-pwm-140x140x25mm-4-pin-2000rpm-max-ip67-fan

I also have 2... (182 cubic m/hr)… https://www.computerlounge.co.nz/shop/components/cooling/fans/noctua-nf-a14-industrial-ppc-2000-pwm-140mm-fan?gclid=CjwKCAjwyvaJBhBpEiwA8d38vDKinEwYxOfBkF6wsy6hGidr46jtPrmIR28t2_lLnKNvJUpqABD_7RoCJIkQAvD_BwE and was thinking to put them on the front middle and top as intake fans.

=679 cubic m/hr air in.

427 cubic m/hr air out and 679 cubic m/hr air in. Is this too much of a disparity from air in to out? Which is better, more going out or more going in?
 
Last edited:
Oct 23, 2020
85
1
35
0
Fan is the thingy like a propeller with blades turning and producing wind.
Radiator is thingy same but smaller than one in any car and certainly smaller than on bus, full with water and is to transfer heat energy from CPU to a better place.
Yes you can use a splitter (with right number of wires) to connect 2 fans together to one receptacle on the MB, they'll run at same speed as adjusted by BIOS.
Is it ok to have a spare lead? For example, if I plug 2 fans into a 3 leaded splitter, is it ok for the 3rd lead to be idle and not used?
 
It's OK but must warn you, they are quite noisy comparing to "normal" ones. Yes they would turn same speed when connected like that.
 
Oct 23, 2020
85
1
35
0
It's OK but must warn you, they are quite noisy comparing to "normal" ones. Yes they would turn same speed when connected like that.
Thanks again,

I'll be using them for Sim racing and will be wearing headphones anyway. Summers are warm here so want some protection against that, hehe.
 

Paperdoc

Champion
Ambassador
OK, I'll review a few points from your plans.
  1. The CPU cooler system is a heatsink and fan mounted on the CPU, and plugged into the CPU_FAN header. It draws air from inside the case, and discharges its warmed air also inside the case. It is NEITHER an Intake nor an Exhaust fan. So do NOT count it in case fan air flow balance.
  2. You've listed two fan models in the Noctua iPPC 2000 line. ALL are basically the SAME model - the only difference is one type (the IP67 model) is dated for water resistance. There are NO differences among them for speed, air flow rate, pressure, max amps electrical draw, etc.
  3. The websites you linked to for the fans got their air flow ratings wrong. If you go to the Noctua site for the NF-A14 iPPC-2000 IP67 PWM model (or the non-IP67) the max air flow rating on them is 182.5 m³/hr. At max speed each will draw 0.18 A current. So, if you mount THREE of these as front intakes and ONE as rear exhaust, there will be a substantial (3:1) difference in air flow RATING, intake versus exhaust. (Of course, actual air flows in and out will be the SAME, and close to the rating of the limiting single rear fan.) You will get better total air flow and cooling of the case if you do two Intakes and two Exhausts. In your case, I'd suggest front intakes at bottom and middle, one exhaust at TOP rear, and one exhaust at rear near the top.
  4. With max amp draws of 0.18 A per fan, you CAN connect up to four of these fans together using a single Splitter to one fan header. The header's limit is 1.0 A total load. Oh, and yes, you can leave one output arm of a Splitter empty. You REALLY should ensure that the one Splitter arm with ALL FOUR pins in its output connector IS used for one of the fans.
  5. However, I suggest you use TWO headers, and two Splitters to connect two fans to each of those headers. Make one header for the Intakes at front, and the other for the two exhausts at top and rear. As a STARTING point, configure both of those headers exactly the same, and they will run all the four fans the same.
  6. Here's why I suggest two fan groups. I consider it ideal if you can have slightly more INTAKE capacity that exhaust. If you do that, there is a small net positive air pressure inside the case. What that means is that at air leakage points the small air flow will be from inside to out, and that prevents entry of unfiltered dusty room air. One problem with this is that the front INTAKE fans must have dust filters in front of them, and this slightly reduces their intake air flow. So from the start with exactly the same number of the same fans, as you will have, the pressure balance is the wrong way. One way to change this is to use the option of a custom "fan curve" to change the automatic fan speed controls for the exhaust fans (together on one header) to run a little slower than the intake fans for all temperatures - see your mobo manual, p. 3-8. You can do this AFTER you get all your other details set up. When you do, you can TEST whether your case has internal positive pressure easily with a smoke tracer. For this you need a small smoke source - a smouldering cigarette or an incense stick. With the system running, move the smoke source near any small leakage cracks in the case and watch which way the smoke blows. If it drifts away slowly from the crack, you have succeeded. If it's sucked into the case, you need to slow down the exhaust fans a bit more. Try this for several workloads, from idle to heavy gaming.
Thanks for Best Solution above.
 
Oct 23, 2020
85
1
35
0
OK, I'll review a few points from your plans.
  1. The CPU cooler system is a heatsink and fan mounted on the CPU, and plugged into the CPU_FAN header. It draws air from inside the case, and discharges its warmed air also inside the case. It is NEITHER an Intake nor an Exhaust fan. So do NOT count it in case fan air flow balance.
  2. You've listed two fan models in the Noctua iPPC 2000 line. ALL are basically the SAME model - the only difference is one type (the IP67 model) is dated for water resistance. There are NO differences among them for speed, air flow rate, pressure, max amps electrical draw, etc.
  3. The websites you linked to for the fans got their air flow ratings wrong. If you go to the Noctua site for the NF-A14 iPPC-2000 IP67 PWM model (or the non-IP67) the max air flow rating on them is 182.5 m³/hr. At max speed each will draw 0.18 A current. So, if you mount THREE of these as front intakes and ONE as rear exhaust, there will be a substantial (3:1) difference in air flow RATING, intake versus exhaust. (Of course, actual air flows in and out will be the SAME, and close to the rating of the limiting single rear fan.) You will get better total air flow and cooling of the case if you do two Intakes and two Exhausts. In your case, I'd suggest front intakes at bottom and middle, one exhaust at TOP rear, and one exhaust at rear near the top.
  4. With max amp draws of 0.18 A per fan, you CAN connect up to four of these fans together using a single Splitter to one fan header. The header's limit is 1.0 A total load. Oh, and yes, you can leave one output arm of a Splitter empty. You REALLY should ensure that the one Splitter arm with ALL FOUR pins in its output connector IS used for one of the fans.
  5. However, I suggest you use TWO headers, and two Splitters to connect two fans to each of those headers. Make one header for the Intakes at front, and the other for the two exhausts at top and rear. As a STARTING point, configure both of those headers exactly the same, and they will run all the four fans the same.
  6. Here's why I suggest two fan groups. I consider it ideal if you can have slightly more INTAKE capacity that exhaust. If you do that, there is a small net positive air pressure inside the case. What that means is that at air leakage points the small air flow will be from inside to out, and that prevents entry of unfiltered dusty room air. One problem with this is that the front INTAKE fans must have dust filters in front of them, and this slightly reduces their intake air flow. So from the start with exactly the same number of the same fans, as you will have, the pressure balance is the wrong way. One way to change this is to use the option of a custom "fan curve" to change the automatic fan speed controls for the exhaust fans (together on one header) to run a little slower than the intake fans for all temperatures - see your mobo manual, p. 3-8. You can do this AFTER you get all your other details set up. When you do, you can TEST whether your case has internal positive pressure easily with a smoke tracer. For this you need a small smoke source - a smouldering cigarette or an incense stick. With the system running, move the smoke source near any small leakage cracks in the case and watch which way the smoke blows. If it drifts away slowly from the crack, you have succeeded. If it's sucked into the case, you need to slow down the exhaust fans a bit more. Try this for several workloads, from idle to heavy gaming.
Thanks for Best Solution above.
Outstanding, thank you very much.

I'm a bit of a idiot so to begin my journey into PC building, I have bought a custom built PC to my specs. I left the fans out so now I'm installing them myself.

At least I'll learn something. The first thing being to go straight to the manufacture's site for any specs... and go from there. (I would have saved money as I don't need the waterproof fans. I live on the land).

Next year I'll be building a second PC with what I've learnt from researching the specs for this first PC.... fingers crossed.

Thanks again, this forum is amazing.
 

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