Question Pwm fans

Paperdoc

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Yes, if you have the proper connector / adapter. The pump wiring is exactly the same as an older 3-pin fan, so an adapter that allows you to power such a fan from a 4-pin Molex or SATA power output connector from the PSU will do the job. Virtually all AIO pumps are designed to operate at full 12 VDC power and run full speed all the time, which is what will happen this way.

However, you will miss out on a useful feature by doing this. All mobo fan headers monitor the speed signal sent back to them from the fan (or pump) connected to them for FAILURE - that is, no speed signal - and warn you if that happens. When you connect the pump to the PSU directly, there is no way for that speed signal to reach the mobo, so such monitoring cannot be done for you. Further, because the CPU chip is so vital and expensive, the CPU_FAN header does extra-intense monitoring usually. On many mobos if there is no speed signal at that header, the mobo may send out its alarm and then, shortly thereafter, completely shut down your system even without waiting for the temperature sensor inside the CPU chip to show high temps. Such systems may even refuse to let you boot up if it gets no speed signal on that header. If you have a system like that and do what you plan, you will need to go into BIOS Setup to the CPU_FAN header and disable this fan failure alarm system.

With that in mind, why do you want to NOT plug your pump into the CPU_FAN header?
 
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Aug 27, 2020
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Yes, if you have the proper connector / adapter. The pump wiring is exactly the same as an older 3-pin fan, so an adapter that allows you to power such a fan from a 4-pin Molex or SATA power output connector from the PSU will do the job. Virtually all AIO pumps are designed to operate at full 12 VDC power and run full speed all the time, which is what will happen this way.

However, you will miss out on a useful feature by doing this. All mobo fan headers monitor the speed signal sent back to them from the fan (or pump) connected to them for FAILURE - that is, no speed signal - and warn you if that happens. When you connect the pump to the PSU directly, there is no way for that speed signal to reach the mobo, so such monitoring cannot be done for you. Further, because the CPU chip is so vital and expensive, the CPU_FAN header does extra-intense monitoring usually. On many mobos if there is no speed signal at that header, the mobo may send out its alarm and then, shortly thereafter, completely shut down your system even without waiting for the temperature sensor inside the CPU chip to show high temps. Such systems may even refuse to let you boot up if it gets no speed signal on that header. If you have a system like that and do what you plan, you will need to go into BIOS Setup to the CPU_FAN header and disable this fan failure alarm system.

With that in mind, why do you want to NOT plug your pump into the CPU_FAN header?
Actually I have 1 fan and one aio cooler with 2 fans. This gives me a total 4 fan header requirement... but I only have 3 headers. where I live its not easy to get my hands on a splitter for worth price(costs around 15$). So I was thinking to plug the pump directly to the psu as it is designed to work on full 12 V.

Plz let me know if my approach is correct or I should buy a splitter instead
 

Paperdoc

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Buying a Splitter is the simplest, but it does cost money and may take time to get it. If you have the skills and the equipment to splice some wires together and solder them for a good electrical connection, you can create your own "splitter" connection for two fans. So, tell us whether you could do that. If you can, we can tell you details of how. By the way, an AIO system that has TWO fans plus a pump often comes with its own Splitter supplied. Did you get one with that system?

Post back here the maker and exact model of motherboard you have. Also tell us what AIO system you have, and what is the fourth fan. With those details we can advise the best connections to make.
 

iPeekYou

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Actually I have 1 fan and one aio cooler with 2 fans. This gives me a total 4 fan header requirement... but I only have 3 headers. where I live its not easy to get my hands on a splitter for worth price(costs around 15$). So I was thinking to plug the pump directly to the psu as it is designed to work on full 12 V.

Plz let me know if my approach is correct or I should buy a splitter instead
Eh, if you can find a Molex to PWM connector easy, sure. More commonly used for case fans, but 3-pin AIO pump is using same interface and have similar power requirements anyway.

Personally, I'd err towards using a powered hub, just not a fancy one. Mine looks more similar to a splitter but with additional power cable to SATA. No plastic casing or anything, just plain PCB with 5x 4-pin PWM connectors. Had mine for $5 or so.

A proper fan hub does cost around $15, the nice looking ones with matte black plastic casing. Plus I imagine having a fan hub is handy for future upgrades when you add fans or other PWM devices.

Alternatively, a plain splitter should work just fine. You're only short 1 connector anyway. Bought my splitter wires for $2-3, and also some of my coolers come with their Y-splitter which is the same thing just shorter.

Amperage shouldn't be an issue, common fans (as in, not Delta/server fans) only draw 0.3A at most. Rarely you see up to 0.6A fans, but they're much less common and surely an AIO wouldn't ship with those kind of fans. You're good up to 1A running splitters or straight to motherboard, and up to 4A or so with SATA powered hubs.

Plug the AIO pump to motherboard, use the a splitter on the AIO fans to a header, plug the last fan to the remaining header. Just my 2 cents.
 
Aug 27, 2020
16
0
10
0
Buying a Splitter is the simplest, but it does cost money and may take time to get it. If you have the skills and the equipment to splice some wires together and solder them for a good electrical connection, you can create your own "splitter" connection for two fans. So, tell us whether you could do that. If you can, we can tell you details of how. By the way, an AIO system that has TWO fans plus a pump often comes with its own Splitter supplied. Did you get one with that system?

Post back here the maker and exact model of motherboard you have. Also tell us what AIO system you have, and what is the fourth fan. With those details we can advise the best connections to make.
Thank you so much for the help sir. Actually I got my hands on a decently priced pwm splitter. Thank you for ur time.
 

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