Multiple fan setup, b450M gaming plus

Vadersoul · 9 Oct 2019 at 10:39

I have never been great on cooling. Usually the exhaust fan is all I ever setup, I know it is naughty.

In a new build now I want to use as much cooling as I can get, however I am limited by the fan setup with only 3 headers (including CPU) on the board.
My case is a Q300L, so I get a spot on the bottom, two on the front, two on the top and the included one on the rear.

NOTE: All of the fans are purchased already, as are the splitters, wasn't sure which option and any that I don't use will go into my partners rig.

My options, using fan splitters (fan+fan) would be

1) (Rear + Top) + (Front + Front) + (CPU)
2) ((Rear + Top) + CPU) + ((Front + Front) + Bottom)

Neither option should take the ampage past the 1.0a I need, as each fan is only .25a (not sure about the amperage on the wraith prism cooler) so either option is possible.

So, aside from the fun task of cable management for 4 splitters instead of 2, the big questions I am looking for advice on are

- Will i get a big enough cooling benefit from having an additional exhaust at the top and intake at the bottom for it to?
- Is there any conflict to the setup that I am not thinking about?
- Should I be trying to get a neutral pressure in their or should I focus on a positive model to exhaust more out, and perhaps go to a 3 exhaust + 2 intake + cpu, that way I can just use a (Rear + CPU) + (Top + Top) + (Front + Front)?

Minibiker · 9 Oct 2019 at 11:32

Personally I do 2 intake at the front and one or two exhaust fans (rear and top) depending on my case.. Ive literally just built an ITX system so not much room but I've gone for one rear exhaust and ordered some Fans for front intake... I've only ever put fans at the bottom when I had my Inwin case which was designed so the PSU was at the top so it was best to have fans on the bottom...

Your case seems to have a decent mesh like panel at the front so a couple of fans bringing cool air in from there would be great...

Vadersoul · 9 Oct 2019 at 11:52

Minibiker said:
Personally I do 2 intake at the front and one or two exhaust fans (rear and top) depending on my case.. Ive literally just built an ITX system so not much room but I've gone for one rear exhaust and ordered some Fans for front intake... I've only ever put fans at the bottom when I had my Inwin case which was designed so the PSU was at the top so it was best to have fans on the bottom...

Your case seems to have a decent mesh like panel at the front so a couple of fans bringing cool air in from there would be great...

As I said, I am new when it comes to cooling.
Does having MORE intake and MORE exhaust matter? Or is it just easier to have 2+2 as much as 3+3?

Minibiker · 9 Oct 2019 at 12:02

Vadersoul said:
As I said, I am new when it comes to cooling.
Does having MORE intake and MORE exhaust matter? Or is it just easier to have 2+2 as much as 3+3?

It is good to keep cool air circulating inside the case... I don't think you'll see a big difference between 3+3 and 2+2 tbh

doyll · 9 Oct 2019 at 12:22

I don't know if running 3x 0.25A fans on single header is advisable. Reason is advertised amp rating is generally running amp load, and startup amp load is 3-5x times more. Startup is also load motors pull if impeller is stopped, like when a bearing seized or something is stuck into fan stopping it from moving. Below link is to PDF showing running and startup load on Gentile Typhoon fans:
http://www.e-jpc.com/pdf/gentle-typhoon-d0925-catalog-2.pdf

If your fan headers are PWM, the best way to control more fans would be to use PWM splitter or hub that uses PSU power and only the PWM signal from motherboard. Motherboard PWM signal is powerful enough to control 7-8 fans no problem.

2x 140mm fans move about the same amount of air as 3x 120mm fans do at similar speed and noise level, so 2x 140mm front intakes will supply more air then 2x 120mm fans. I suggest fans with high static pressure ratings because higher pressure rating means fan can overcome grill & filter resistance and flow more air than lower pressure rated fans can.

I suggest removing all PCIe back slot covers to increase exhaust vent area around GPU which will improve front to back airflow around GPU. Doing this will lower air temp into GPU as well as CPU because less of GPU's heated exhaust can mix with cool air to boht components.

All of my builds in last serveral years only use intake fans. Using both intake and exhaust case fans is same principle as using push / pull fans on radiator or air cooler .. generally push / pull will lower temps at most 2-3c and raise noise level some as well. In a few cases (no pun) using both intake and exhaust can improve airflow paths in the case to component temps are lower .. or may change airflow paths and increase component temps. Experimentation is only way to find out for sure. Link below is to basic guide to how airflow works and how to optimize case airflow may be of interest:
https://forums.overclockers.co.uk/t...-i-put-my-temp-sensor.18564223/#post-26159770

Using flat CPU coolers rather than tower coolers (Wraith Prism cooler is not a tower) makes it much harder to keep cooler's heated exhaust from mixing with cool airflow to cooler. Reason is air flow down through cooler hitting motherboard and turning out where it hits RAM, GPU, etc and turns up along side of cooler and fan where it is drawn back into cooler. Below link to test results of flat cooler w/ fan pulling vs pushing air through cooler showing up to 7c lower temps with fan pulling than pushing. 2nd like is visual of airflow through flat cooler.
https://forums.overclockers.co.uk/threads/best-cooler-for-i5-3570k.18672684/#post-28163640
https://www.overclock.net/forum/22323763-post9.html

I suggest getting a good tower cooler. Scythe Mugen 5 Rev.B would be good.
https://www.overclockers.co.uk/scythe-scmg-5100-mugen-5-rev.b-cpu-cooler-hs-046-sy.html

Ideally we want a little positive pressure because it's easier to filter intake airflow and thus keep dust out of case. I go years without cleaning dust out of my systems, but I do hoover the filters ever other week when hoovering house. Using more exhaust fans means dusty air will be leaking into case through every small opening .. using more intakes means clean air leaks out those same small openings. Keep in mind 3x intakes behind fancy grills and filters may not flow as much air into case as 2x exhaut fans can suck out.

Vadersoul · 9 Oct 2019 at 13:20

doyll said:
I don't know if running 3x 0.25A fans on single header is advisable. Reason is advertised amp rating is generally running amp load, and startup amp load is 3-5x times more. Startup is also load motors pull if impeller is stopped, like when a bearing seized or something is stuck into fan stopping it from moving. Below link is to PDF showing running and startup load on Gentile Typhoon fans:
http://www.e-jpc.com/pdf/gentle-typhoon-d0925-catalog-2.pdf

If your fan headers are PWM, the best way to control more fans would be to use PWM splitter or hub that uses PSU power and only the PWM signal from motherboard. Motherboard PWM signal is powerful enough to control 7-8 fans no problem.

2x 140mm fans move about the same amount of air as 3x 120mm fans do at similar speed and noise level, so 2x 140mm front intakes will supply more air then 2x 120mm fans. I suggest fans with high static pressure ratings because higher pressure rating means fan can overcome grill & filter resistance and flow more air than lower pressure rated fans can.

I suggest removing all PCIe back slot covers to increase exhaust vent area around GPU which will improve front to back airflow around GPU. Doing this will lower air temp into GPU as well as CPU because less of GPU's heated exhaust can mix with cool air to boht components.

All of my builds in last serveral years only use intake fans. Using both intake and exhaust case fans is same principle as using push / pull fans on radiator or air cooler .. generally push / pull will lower temps at most 2-3c and raise noise level some as well. In a few cases (no pun) using both intake and exhaust can improve airflow paths in the case to component temps are lower .. or may change airflow paths and increase component temps. Experimentation is only way to find out for sure. Link below is to basic guide to how airflow works and how to optimize case airflow may be of interest:
https://forums.overclockers.co.uk/t...-i-put-my-temp-sensor.18564223/#post-26159770

Using flat CPU coolers rather than tower coolers (Wraith Prism cooler is not a tower) makes it much harder to keep cooler's heated exhaust from mixing with cool airflow to cooler. Reason is air flow down through cooler hitting motherboard and turning out where it hits RAM, GPU, etc and turns up along side of cooler and fan where it is drawn back into cooler. Below link to test results of flat cooler w/ fan pulling vs pushing air through cooler showing up to 7c lower temps with fan pulling than pushing. 2nd like is visual of airflow through flat cooler.
https://forums.overclockers.co.uk/threads/best-cooler-for-i5-3570k.18672684/#post-28163640
https://www.overclock.net/forum/22323763-post9.html

I suggest getting a good tower cooler. Scythe Mugen 5 Rev.B would be good.
https://www.overclockers.co.uk/scythe-scmg-5100-mugen-5-rev.b-cpu-cooler-hs-046-sy.html

Ideally we want a little positive pressure because it's easier to filter intake airflow and thus keep dust out of case. I go years without cleaning dust out of my systems, but I do hoover the filters ever other week when hoovering house. Using more exhaust fans means dusty air will be leaking into case through every small opening .. using more intakes means clean air leaks out those same small openings. Keep in mind 3x intakes behind fancy grills and filters may not flow as much air into case as 2x exhaut fans can suck out.

Thank you.

RE: Fan size, I am just going with 120MM, non-PWM. I believe I can still change the speed in software via MSI motherboard so that is good.
RE: Ampage, I did not know that and running 3 didn't sound ideal, so perhaps sticking to two split (which seems standard)
RE: Positive Pressure, so is it worth going 2 in the front, 2 at the top, 1 at the back (all 120MM) which will be a 2:3 intake:exhaust ratio and then with one for the CPU, that leaves me with 6 fans, split across 3 headers with 2:1 for each header

That sounds like the best plan?

doyll · 9 Oct 2019 at 14:16

What fans exactly are you going with? PWM or variable voltage control make little difference unless wanting to control more than 2 fans on one mobo header. If wanting more fans to be controlled by single header PWM is only way to do it.

Using splitters safely is dependent on what fan header is rated for (usually 1 amp max) and what fan startup load is. If you have ever heard of / read about someone burning out a fan header it's always when system is starting up or if a fan bearing seized .. when fan motor draws startup load .. which is many times more current than running load rating.

"Positive pressure" is almost a myth because even highest pressure computer fans only make about as much pressure differential as there is between standing with feet in the other and standing on a dock 10 feet above sea level .. extremely low pressure differnce. I would run more intakes than exhaust simply because it keep dust out when all intakes have filters.

Read the airflow and optimizing case airflow guide I linked in previous post. It give more detail about how and why I setup systems as I do.

Vadersoul · 9 Oct 2019 at 14:35

doyll said:
What fans exactly are you going with? PWM or variable voltage control make little difference unless wanting to control more than 2 fans on one mobo header. If wanting more fans to be controlled by single header PWM is only way to do it.

Using splitters safely is dependent on what fan header is rated for (usually 1 amp max) and what fan startup load is. If you have ever heard of / read about someone burning out a fan header it's always when system is starting up or if a fan bearing seized .. when fan motor draws startup load .. which is many times more current than running load rating.

"Positive pressure" is almost a myth because even highest pressure computer fans only make about as much pressure differential as there is between standing with feet in the other and standing on a dock 10 feet above sea level .. extremely low pressure differnce. I would run more intakes than exhaust simply because it keep dust out when all intakes have filters.

Read the airflow and optimizing case airflow guide I linked in previous post. It give more detail about how and why I setup systems as I do.

So the only thing I am debating right now is do I go 2 front, 2 rear (all non pwm) and aim for a mostly neutral air pressure setup.
Or, do I go for a negative pressure or positive pressure system where I am pulling 3 fans in and 2 out, or 2 fans in and 3 out. The disadvantage though is that I won't be able to control the fans equally.

Tempted to a 2+2 for simplicity, reading some of these comments. Is that a good idea?

doyll · 9 Oct 2019 at 15:15

Vadersoul said:
So the only thing I am debating right now is do I go 2 front, 2 rear (all non pwm) and aim for a mostly neutral air pressure setup.
Or, do I go for a negative pressure or positive pressure system where I am pulling 3 fans in and 2 out, or 2 fans in and 3 out. The disadvantage though is that I won't be able to control the fans equally.

Tempted to a 2+2 for simplicity, reading some of these comments. Is that a good idea?

You still haven't told me what brand and model your cases fans are.

2x front intake and 2x rear exhaust would have more exhaust pull than intake because exhaust vents don't have added resistance of filters. Honest, you do not need matching exhaut fans. do yourself a favor and try it with 2x front intakes, all PCIe back slot covers removed and no exhaust fan. If exhaust fans are already in case just unplug for the test.

Keep in mind you need more intake (and exhaust) airflow through case than the CPU and GPU fans are using to even have a chance at supplying coolers with air at or near room temp. Any less airflow means cooler fans have to re-use their own heated air to get the airflow they are using.

Steveocee · 9 Oct 2019 at 15:20

Keep the air going in one direction if you can, front to back normally. Try to get more going in than out (slight positive pressure).
Use as bigger fans as you can e.g. Two 140mm's are preference over Three 120mm's.

doyll · 9 Oct 2019 at 15:25

What Steveocee said.

The straighter the air flows the less turbulence it has to mix and slow down. Sraight and smooth is important.

Vadersoul · 9 Oct 2019 at 15:29

doyll said:
You still haven't told me what brand and model your cases fans are.

2x front intake and 2x rear exhaust would have more exhaust pull than intake because exhaust vents don't have added resistance of filters. Honest, you do not need matching exhaut fans. do yourself a favor and try it with 2x front intakes, all PCIe back slot covers removed and no exhaust fan. If exhaust fans are already in case just unplug for the test.

Keep in mind you need more intake (and exhaust) airflow through case than the CPU and GPU fans are using to even have a chance at supplying coolers with air at or near room temp. Any less airflow means cooler fans have to re-use their own heated air to get the airflow they are using.

Sorry, I didn't realise there was a question on that, I may have missed it.

Artic non-Pmw 120mm fans, cheap bottom shelf stuff really.

Not a fan of removing my back slots, but I do have blanking plates with filters on them so plan on using those for the 3 free slots. Don't really want a place for dust/hair to settle inside the case with a big open vent for it to enter.

So it seems like the best course of action proposed here, would be to go for a 2+1 intake:exhaust ratio and aim for a positive pressure setup that is driving those front fans one direction across the case (front to back) without pulling it up.
I am warm to this idea (no pun intended)... Would save some hassle.

doyll · 9 Oct 2019 at 15:40

Vadersoul said:
Sorry, I didn't realise there was a question on that, I may have missed it.

Artic non-Pmw 120mm fans, cheap bottom shelf stuff really.

Not a fan of removing my back slots, but I do have blanking plates with filters on them so plan on using those for the 3 free slots. Don't really want a place for dust/hair to settle inside the case with a big open vent for it to enter.

So it seems like the best course of action proposed here, would be to go for a 2+1 intake:exhaust ratio and aim for a positive pressure setup that is driving those front fans one direction across the case (front to back) without pulling it up.
I am warm to this idea (no pun intended)... Would save some hassle.

They work okay. If they don't move enough air Arctic P12 series are better and also low cost.

Slot covers with grill will restrict at least have of airflow you would have with open slots.

What CPU cooler and what GPU do you have? I ask so I will be able to say 2x 120mm fans will supply enough air to them. Like I said in my last post, you need case fans to move more air though case than the componet fans (CPU and GPU) use. If you do not have more case airflow the cooler fans have to re-use their own heated exhaust .. and every degree warmer the air is going into cooler is degree hotter CPU and/or GPU will be.

Vadersoul · 9 Oct 2019 at 15:41

Steveocee said:
Keep the air going in one direction if you can, front to back normally. Try to get more going in than out (slight positive pressure).
Use as bigger fans as you can e.g. Two 140mm's are preference over Three 120mm's.

I already have the fans, so although I can buy more, I would prefer not to.

Based on the current advice, it seems that I should just go with 2 intake and 1 exhaust at the rear, keep it going straight and avoid venting up instead of to the back.

However, since I only have 2 x 120MM fans and wouldn't be able to squeeze another in there, is there value in putting one on the bottom (both bottom and front are filtered on this case) and go for a 3:1 ratio?

Vadersoul · 9 Oct 2019 at 15:43

doyll said:
They work okay. If they don't move enough air Arctic P12 series are better and also low cost.

Slot covers with grill will restrict at least have of airflow you would have with open slots.

What CPU cooler and what GPU do you have? I ask so I will be able to say 2x 120mm fans will supply enough air to them. Like I said in my last post, you need case fans to move more air though case than the componet fans (CPU and GPU) use. If you do not have more case airflow the cooler fans have to re-use their own heated exhaust .. and every degree warmer the air is going into cooler is degree hotter CPU and/or GPU will be.

They are F12s.

It is a Wraith Prism (Ryzen 7 3700x) and a PowerColor 5700 XT (same it looks as the regular AMD, blower style)
So, in the case of the CPU, hot air is being pushed down to the board and in the case of the GPU, hot air is being pushed to the base of the case (PSU)

doyll · 9 Oct 2019 at 15:54

Vadersoul said:
They are F12s.

It is a Wraith Prism (Ryzen 7 3700x) and a PowerColor 5700 XT (same it looks as the regular AMD, blower style)
So, in the case of the CPU, hot air is being pushed down to the board and in the case of the GPU, hot air is being pushed to the base of the case (PSU)

Can fan on Wraith Prism be turned over? That alone usually lowers temps by 4-8c because it move heated air away for cooler. Think fan is about 120mm so might be able to use a 120mm instead held on with rubber bands or zip-ties. PowerColor 5700 XT has 2x 80/90mm fans and dumps more air away from motherboard and toward front of cae than it does against mobo.

Basically you need at least 3x 120mm intakes to supply enough air for your components.

Vadersoul · 9 Oct 2019 at 17:32

doyll said:
Can fan on Wraith Prism be turned over? That alone usually lowers temps by 4-8c because it move heated air away for cooler. Think fan is about 120mm so might be able to use a 120mm instead held on with rubber bands or zip-ties. PowerColor 5700 XT has 2x 80/90mm fans and dumps more air away from motherboard and toward front of cae than it does against mobo.

Basically you need at least 3x 120mm intakes to supply enough air for your components.

No

... Not excited about hooking something up with zip ties.

Couldn't I try and get the bottom fan working for that though?
Surely with the cross intake, it should drive the airflow forward towards the rear still, right?