Little confused with PWM stuff

[Heimatt]

Hey guys.

 

My computer crashes quite a bit these days (kernel power 42 nonsense) and when it crashes it's really freaking hot.

 

I have a fractal meshify 2. For the cooling solutions, I have the 2 fractal 3 pin 140mm fans in front, one other behind, and 2 PWM 4 pins 120mm 1500 RPM fans on top of the system to extract hot air.

 

I have an ARCTIC Case Fan Hub but it only works with 4 pin fans.

 

I would like to replace my 3 3 pin fans that i don't manage to tune properly in bios and put all 5 PWM fans on it with an agressive curve (noise is not so much of an issue) related to my CPU temperature.

 

Since the 3 fans from the case are 140 mm and have a strategic position, how would the system behaves if i put 3000 RPM PWM fans? I would have both 1500 and 3000 RPM fabs on my ARCTIC Case Fan Hub. How would it behave? Should i put a 1500 or 3000 RPM fan on header 1 (which is the one returning RPM to the motherboard) ?

 

I hope my weird post is understandable. Thanks for your help

[Poinkachu]

13 minutes ago, Heimatt said:

Hey guys.

 

My computer crashes quite a bit these days (kernel power 42 nonsense) and when it crashes it's really freaking hot.

 

I have a fractal meshify 2. For the cooling solutions, I have the 2 fractal 3 pin 140mm fans in front, one other behind, and 2 PWM 4 pins 120mm 1500 RPM fans on top of the system to extract hot air.

 

I have an ARCTIC Case Fan Hub but it only works with 4 pin fans.

 

I would like to replace my 3 3 pin fans that i don't manage to tune properly in bios and put all 5 PWM fans on it with an agressive curve (noise is not so much of an issue) related to my CPU temperature.

 

Since the 3 fans from the case are 140 mm and have a strategic position, how would the system behaves if i put 3000 RPM PWM fans? I would have both 1500 and 3000 RPM fabs on my ARCTIC Case Fan Hub. How would it behave? Should i put a 1500 or 3000 RPM fan on header 1 (which is the one returning RPM to the motherboard) ?

 

I hope my weird post is understandable. Thanks for your help

If you put all of them on the same hub, it basically depends on which fan you put as the "Guide" or basically the one you plug into the usually red colored header on the hub.
Because the rest will be tuned based on that one.

 

Example if you put 3000rpm one as the guide, and you set it to 50% speed so you can get 1500rpm at 50c , then all other 3000rpm ones will spin at 50% (1500rpm) when temp reaches 50c, while the 1500rpm gonna spin at 50% (750rpm).

 

Just split the header IMHO. put all 3000 rpm ones (which in this case the intake) on 1 header (or hub then header)

Then put all 1500rpm ones on other header.

 

You can just get a 3 way splitter cable and put all the 3pin fans on that splitter, connected to a header on the mobo. Then in bios set to control the fans on that particular header using DC instead of PWM.

 

Then for the PWM fans you put them on a different header, and control them in BIOS using PWM mode.

 

Also, IIRC "Kernel 42" is basically a code for -basically- sudden loss of power

What is your full spec?   Because Meshify 2 is not an oven case

[Tetras]

Unless I'm being a dumb, if you're happy with an aggressive curve, does it even matter if you switch the 3 pins to 4 pin, since won't they be running near full pelt right now anyway?

[Jurrunio]

Your direction feels wrong, when a CPU overheats hard it usually means the cooler is failing its job completely. Say the pump of an AIO died, or the thermal paste has dried out. Doubling fan speeds of already not-slow fans would not help enough to turn a "really freaking hot" CPU into a cool CPU, at best it will last a bit longer before crashing.

 

PWM controls fans based on %, regardless of the actual max RPM of the fans. 3pin fans on a 4pin connector will just run 100% all the time. If you don't care about noise, honestly I don't see that as a reason to not try max fan speeds all the time first and see if the problem goes away. 3000RPM fans are just as loud at similar RPMs to slower fans anyways.

[Heimatt]

2 hours ago, Poinkachu said:

 

 

Example if you put 3000rpm one as the guide, and you set it to 50% speed so you can get 1500rpm at 50c , then all other 3000rpm ones will spin at 50% (1500rpm) when temp reaches 50c, while the 1500rpm gonna spin at 50% (750rpm).

 

 

So PWM asks for x% of max RPM, not X RPM? It's perfect this way! thanks!

[Poinkachu]

1 hour ago, Heimatt said:

So PWM asks for x% of max RPM, not X RPM? It's perfect this way! thanks!

Well that's how the usual tuning is done in the BIOS.

 

But yep, as @Jurrunio said, if you crashed to seriously high overheat, most often there's a whole other problem than just "Not stronk enough fans".

Especially with how modern parts are designed, which is to throttle down when thermal is high.

Unless it's absurd level, in which case then yes it will shut down as a safety system.

 

 

 

[thrasher_565]

1 hour ago, Heimatt said:

So PWM asks for x% of max RPM, not X RPM? It's perfect this way! thanks!

pwm is a % 50% on 50% off voltage dose not change with pwm. saving you 50% power

dc is 12v= 100% 11v = say 90% example

 

Edited September 23, 2023 by thrasher_565

[Jurrunio]

5 minutes ago, thrasher_565 said:

pwm is a % 50% on 50% off voltage dose not change with pwm. saving you 50% power

dc is 12v= 100% 11v = say 90% example

 

This does not explain why 3pin fans on 4pin header runs max speed regardless and 4pin fans on 4pin header can appear to twitch at very low fan speed %. PWM is actually a "if there is power on the 4th pin, cut power" design, not lower voltage. You're describing fan speed control on 3pin headers.

[thrasher_565]

9 minutes ago, Jurrunio said:

This does not explain why 3pin fans on 4pin header runs max speed regardless and 4pin fans on 4pin header can appear to twitch at very low fan speed %. PWM is actually a "if there is power on the 4th pin, cut power" design, not lower voltage. You're describing fan speed control on 3pin headers.

no im not... im describing what pwm is...

you have to have a 4pin to have pwm...

some mb can simulate pwm on a 3pin by truing it on and off.

 

 

Edited September 23, 2023 by thrasher_565

[thrasher_565]

ok so you think using less voltage wouls save on power right kinda... well going from 12v to say 8v the reduced power has to go some ware in form of heat using a varaible resistor or pot. using 100% of 12v vs using 8v and sheding the rest is better and saves power.

 

the psu cant send you 8v of power so there a pot/restorer that sheds some power in heat to get 8v

 

if you had say 2 psu's one that is 12v and one that is 8v and switch between them that would be fine. like going form 12v to 5v for example. molex can do 12v, 5v, and 7v. sata can do 3.3v thow alot of fans need x amount of power to get the fan spinning.

 

most people that have 3pin fans are old and use alot of power yes you can buy newer 3 pin fans that use less power but most people would just got for pwm any way.

 

yes hier then 12v would even be better like 24v and 48v but desktop pcs dont use 24v or 48v. some server do thow.

then you get in to phases witch is basically different amount of voltage and amps. once a motor gets up to speed it needs less power to keep it at that speed saving power. or pulsing it to save power...and use some of the stored energy in the fan.

 

something like that...

Edited September 23, 2023 by thrasher_565

[RevGAM]

21 hours ago, Heimatt said:

Hey guys.

 

My computer crashes quite a bit these days (kernel power 42 nonsense) and when it crashes it's really freaking hot.

 

I have a fractal meshify 2. For the cooling solutions, I have the 2 fractal 3 pin 140mm fans in front, one other behind, and 2 PWM 4 pins 120mm 1500 RPM fans on top of the system to extract hot air.

 

I have an ARCTIC Case Fan Hub but it only works with 4 pin fans.

 

I would like to replace my 3 3 pin fans that i don't manage to tune properly in bios and put all 5 PWM fans on it with an agressive curve (noise is not so much of an issue) related to my CPU temperature.

 

Since the 3 fans from the case are 140 mm and have a strategic position, how would the system behaves if i put 3000 RPM PWM fans? I would have both 1500 and 3000 RPM fabs on my ARCTIC Case Fan Hub. How would it behave? Should i put a 1500 or 3000 RPM fan on header 1 (which is the one returning RPM to the motherboard) ?

 

I hope my weird post is understandable. Thanks for your help

Hubs, even repeaters, that draw power from the PSU can usually do 1A per port. Mobo headers are usually the same 1A, although sometimes some offer more. In other words, you need to pay attention to the max amperage of your fans so you don't burn out a header and/ or fans by putting too many on one. 

 

3-pin (DC) fans run at max speed all the time unless you have something that can vary the volts to slow it down, like a hub. They can be run on a 4-pin PWM hub, splitter, repeater or header, but if it doesn't have that feature...100%.

 

PWM uses the 4th pin to send info which can modulate the speed by pulsing it. Some 3-pin hubs, etc. claim to support PWM but, without that 4th pin, they don't really fully support it. 

 

If you look at splitters and daisy chain cables on fans, you'll see that the socket for the next fan is missing a pin. This is because the 1st fan in the chain (usually port 1 or 0 on a hub, and it may be a red port) sends the info for the mobo, and so all of the fans chained together are controlled bases on that 1st fan.