Swapping fans on heatsink with 120+140mm fans

[doug_locke]

12 hours ago, RevGAM said:

A few months ago, I saw (maybe here?) how someone installed ducting from fan to GC, from fan to CPU, and achieved better temps for both, so I think you should look at that instead of just baffles. Another person did something similar but used different material, and had cold air from their AC directed to the intake. Naturally, that worked well.

.

I've worked with shrouds and ducts in previous cases.  Won't help here.

 

The GPU already get more than enough outside air blowing directly at it from the 3 bottom intake fans. 

 

The only issues here are extra top exhaust prevent the CPU fan from drawing air. 

 

Any duct to feed  the CPU would further obstruct the warm air raising up from the GPU from escaping.

 

One possibility for a duct to help is use an 80mm fan & duct as the middle top exhaust fan so it plan only pull on air that isn't pulled on by the CPU intake. But it won't add any befit to the GPU's rising heat 

 

 

Also Making the area the PC is on colder is great but ac's work my pumping 10-15°C air, if someone pumps that directly inside the case, the many parts that don't heat up much will remain frigid. Moisture from worm air will condense on those cold parts and dri down (this is exactly how a dehumidifier works). Having  large amout of humidity in your PC is never good long term. It's the same reason why people incorporate peltiersvon the button of a gaming laptop

[TatamiMatt]

14 hours ago, doug_locke said:

I can only speak of my 6750xt. My CPU won't thermally throttle but Benchmarks don't improve past 50mhz OC. My throttles often at 2.9ghz (top fun push/pull) and my superposition score is lower than 2.85ghz. That extra couple of degrees from 1 top exhaust exhaust fan gives a slightly better score at 2.9ghz (superposition 1440p score 4.5k vs 4.38k)

 

 

If you don't already own 2 or 3 top fans don't get them. It does very little but adds a lot more noise to the room. I have the extra fan for the RGB but leaving it at 0rpm is the best option.

 

If I use  only 1 top exhaust as a baseline temp(+/- 0° GPU $ GPU undervolted w/no OC )

it's roughly 

2 top exhaust=CPU +3°, GPU -2°

3 top exhaust= CPU +4°, GPU -3°

1 top exhaust, 1 top intake= CPU -2°, GPU +2°

1 top exhaust, 2 top intake=CPU -2°, GPU +3°

 

^^this is with top fan #2&3 set to 60% rpm. At 100% temps go crazy.

 

I'd guess if your GPU was small (<220mm) push/pull top fans are fine either way.

 

Big 3 fan 320mm GPU's (like yours and mine) sticks out far past the the CPU heatsink and the GPU fans are going to cool one side of the GPU... The backside doesn't get as hot but does generate some heat.

 

3x120mm bottom fans push radiating heat upwards a top intake feeds cold air to the CPU but also pushes the heat going upwards back down keeping the GPU warmer. Even with baffles and diagonal fans I cant see a way extra top fans to help one thing without hurting the other.

 

...these aren't real world conditions I doubt many games will push a CPU to 100% but many modern games (ie)  Cyberpunk or even a 5y/o game like Borderlands 3  will push my 6750XT or your 7800xt to 100% and still never get a close to 200fps at 1440p (w a decent GPU overclock cyberpunk gets 6750= 60fps 7800=90fps).

 

TLDR: there is no best config even with identical case/CPU/GPU, there will always be some tradeoff even if noise wasn't a factor

 

 

 

 

 

 

 

I was able to pull around ~110fps on 1440p ultra, quality FSR, 70% sharpening and around 115/120 OC'd, running at about 60/70C hotspot

 

1 hour ago, doug_locke said:

.

I've worked with shrouds and ducts in previous cases.  Won't help here.

 

The GPU already get more than enough outside air blowing directly at it from the 3 bottom intake fans. 

 

The only issues here are extra top exhaust prevent the CPU fan from drawing air. 

 

Any duct to feed  the CPU would further obstruct the warm air raising up from the GPU from escaping.

 

One possibility for a duct to help is use an 80mm fan & duct as the middle top exhaust fan so it plan only pull on air that isn't pulled on by the CPU intake. But it won't add any befit to the GPU's rising heat 

 

 

Also Making the area the PC is on colder is great but ac's work my pumping 10-15°C air, if someone pumps that directly inside the case, the many parts that don't heat up much will remain frigid. Moisture from worm air will condense on those cold parts and dri down (this is exactly how a dehumidifier works). Having  large amout of humidity in your PC is never good long term. It's the same reason why people incorporate peltiersvon the button of a gaming laptop

I also live in a slightly colder climate so we dont have aircon as a norm, i have real high cfm fans as case fans and have 2x140mm and 1x120mm on front intake, the 3x120mm on side intake, and another 140mm top intake. So my intake is more than fine, then im running 1x40mm, 2x120mm exhaust, it doesnt balance super well but its a big case and allows air to flow easily, so any excess pressure has no bother exhausting itself with no issue

[TatamiMatt]

14 hours ago, RevGAM said:

A few months ago, I saw (maybe here?) how someone installed ducting from fan to GC, from fan to CPU, and achieved better temps for both, so I think you should look at that instead of just baffles. Another person did something similar but used different material, and had cold air from their AC directed to the intake. Naturally, that worked well.

I think you'll find this interesting if you havent seen it already rev

 

also @doug_locke

 

 

[RevGAM]

6 hours ago, doug_locke said:

The only issues here are extra top exhaust prevent the CPU fan from drawing air. 

 

Any duct to feed  the CPU would further obstruct the warm air raising up from the GPU from escaping.

Extra where?

 

Compensate by making sure the duct doesn't take up the entire space in that region, and use stronger fans on top to pull the air past it...?

4 hours ago, TatamiMatt said:

I also live in a slightly colder climate

I thought you lived with Santa? Oh, wait, that's @NorKris!

 

4 hours ago, TatamiMatt said:

I think you'll find this interesting if you havent seen it already rev

 

also @doug_locke

 

 

Perfect! Exactly what I'm talking about!

[doug_locke]

8 hours ago, TatamiMatt said:

I think you'll find this interesting if you havent seen it already rev

 

also @doug_locke

 

 

This is pretty cool, And his temps dropped quite a bit. But he also says that it's noe only a few degrees warmer than a test-bench or open air case. 

 

A decent not neccisarilly expensive, gaming case should have the same or lower temps than an open air case before doing intricate mods.

[doug_locke]

9 hours ago, TatamiMatt said:

I was able to pull around ~110fps on 1440p ultra, quality FSR, 70% sharpening and around 115/120 OC'd, running at about 60/70C hotspot

 

I also live in a slightly colder climate so we dont have aircon as a norm, i have real high cfm fans as case fans and have 2x140mm and 1x120mm on front intake, the 3x120mm on side intake, and another 140mm top intake. So my intake is more than fine, then im running 1x40mm, 2x120mm exhaust, it doesnt balance super well but its a big case and allows air to flow easily, so any excess pressure has no bother exhausting itself with no issue

Do you have bottom intake? On my old budget case, taking off a few of the PCI slot covers and sticking a cheap quiet 92mm fan made a huge difference in GPU temps.

[doug_locke]

1 hour ago, doug_locke said:

This is pretty cool, And his temps dropped quite a bit. But he also says that it's noe only a few degrees warmer than a test-bench or open air case. 

 

A decent not neccisarilly expensive, gaming case should have the same or lower temps than an open air case before doing intricate mods.

P.s. I did a similar mod on my antec 300 with the stock phenom 70mm heatsink. I put a hole in the side panel (poorly) Added a fan guard, an 80rpm fan to feed air to the CPU, and a duct. 

 

(It did nothing so I took it all out and covered the hole with a piece of blue abs. I also turned the 120mm side intake to a 140mm, which also did nothing)

 

I tried to reuse that case in the current build but would've had to cut the drive cage to fit the GPU. The case was such an abomination It seemed worth it to drop $90 on a new case. I do miss the 12 HDD capacity.

 

[freeagent]

You don’t need ducts.. just move some air..

 

 

[TatamiMatt]

14 hours ago, doug_locke said:

Do you have bottom intake? On my old budget case, taking off a few of the PCI slot covers and sticking a cheap quiet 92mm fan made a huge difference in GPU temps.

No bottom intake but plenty enough fans providing GPU with air, i have a pic here somewhere...

 

[RevGAM]

13 hours ago, freeagent said:

You don’t need ducts.. just move some air..

 

 

🌬🌪

My lungs aren't strong enough. I guess I'll fart.  

[doug_locke]

8 hours ago, TatamiMatt said:

No bottom intake but plenty enough fans providing GPU with air, i have a pic here somewhere...

 

Ok I see why you wouldn't want more than 1 top exhaust I'm sure you know what you're doing... but just in case:

1)with 2 heatsink fans, having a fan blowing onto the front of each tower performs much better than putting one in the middle and back. 

2)if you're using side and front intake, keeping the side at a much lower rpm will usually improve or not change temps. (The 120's may have lower cfm but the smaller area mean the first few inches have more pressure so they're pushing onto front intake air, reducing how much air gets in from the front

Easy test: the side intake just needs to blow hard enough that, a piece  tissue paper, placed on the back of the side fan is barely held in place by suction when side & front fans are running and the side panel is on (*or piece of newspaper, receipt paper, or anything lighter than printer paper). Turn the rpm down til the paper starts to fall. That speed,or a little less, should be an optimal max speed for the side fans. 

[TatamiMatt]

24 minutes ago, doug_locke said:

1)with 2 heatsink fans, having a fan blowing onto the front of each tower performs much better than putting one in the middle and back. 

Yeah i know, but i like my RAM rgb, it was a concious decision and there wasnt any noticable temp change outside of margin of error, the FC140 is overkill for the 7800X3D anyway

24 minutes ago, doug_locke said:

2)if you're using side and front intake, keeping the side at a much lower rpm will usually improve or not change temps. (The 120's may have lower cfm but the smaller area mean the first few inches have more pressure so they're pushing onto front intake air, reducing how much air gets in from the front

Easy test: the side intake just needs to blow hard enough that, a piece  tissue paper, placed on the back of the side fan is barely held in place by suction when side & front fans are running and the side panel is on (*or piece of newspaper, receipt paper, or anything lighter than printer paper). Turn the rpm down til the paper starts to fall. That speed,or a little less, should be an optimal max speed for the side fans. 

I plan on configuring them like that eventually, right now theyre on the same PWM signal for handiness sake, but im waiting on my last 3pack of 120mm fans (6 months later, finally) to standardise the look and for performance, then ill tweak for best temps, currently GPU runs around 60C hotspot, cpu at 50C while gaming and VRMs dont get past 35C, so temps are fine, also thats an old photo, i have sacrificed a few of the non rgb fans for another computer i built my parents from other salvaged parts but overall still fine temps, maybe +1-4C on average with the less fans

 

(in reference to part 1)

 

Fan specs:

 

120mm

 

140mm

 

Theyre not the best fans on the market nor do they live up to their specs, but i bought them at £45 for a 3pack, they have very nice rgb, daisy chainable rgb and as far as case fans go theyre quite good, a little loud but more than adequate performance for their use case

 

To sum up:

 

Positives                                                             Negatives

-very good performance                                   -they are however beaten by a lot of other fans

-very nice rgb                                                    -decently loud

-for what i bought them for, quite cheap

[doug_locke]

4 hours ago, TatamiMatt said:

Yeah i know, but i like my RAM rgb, it was a concious decision... right now theyre on the same PWM signal for handiness sake...

 

(in reference to part 1)

 

Fan specs:

 

120mm

 

140mm

 

Theyre not the best fans on the market nor do they live up to their specs

Half you tried clipping the 140mm heatsink fan to the other side, so each tower has 1 fan pulling on it? Might be better and wont effect the appearance at all.

 

If it were me (I like going overboard), I'd also stick a 10-15mm thick 70mm RGB fan high up on the front cooler tower (a cheap generic chinese one)

...So I could Still see the ram rgb light up the front of the heatsink, and get 40+ cfm blowing  on 3 of the heat pipes (FC140's center 3 pipes do 90% of the work in Ryzen chips) 

 

Those 120's are very powerful for case fans (half the pressure and cfm would still be above average) surprised it made any temp difference with less fans. 

 

 

My swapped my 120mm 82cfm  (blue led) fans for 66cfm center lit rgb fans. Then swapped 4 of those for 48cfm center+ outer ring RGB fans. 100% rpm 82cfm fans=same temps as 80% speed 66/48 cfm fans. 

 

Only the rear exhaust improves temps at full speed

 

 

[TatamiMatt]

14 hours ago, doug_locke said:

Half you tried clipping the 140mm heatsink fan to the other side, so each tower has 1 fan pulling on it? Might be better and wont effect the appearance at all.

 

If it were me (I like going overboard), I'd also stick a 10-15mm thick 70mm RGB fan high up on the front cooler tower (a cheap generic chinese one)

...So I could Still see the ram rgb light up the front of the heatsink, and get 40+ cfm blowing  on 3 of the heat pipes (FC140's center 3 pipes do 90% of the work in Ryzen chips) 

 

Those 120's are very powerful for case fans (half the pressure and cfm would still be above average) surprised it made any temp difference with less fans. 

 

 

My swapped my 120mm 82cfm  (blue led) fans for 66cfm center lit rgb fans. Then swapped 4 of those for 48cfm center+ outer ring RGB fans. 100% rpm 82cfm fans=same temps as 80% speed 66/48 cfm fans. 

 

Only the rear exhaust improves temps at full speed

 

 

Yeah thats an old photo, the fan is attached to the front tower, this photo was taken mid swap over, also rotated its now 90degrees as the fan is actually 152x140mm outer so now sits a little lower and hits more fins and heatpipe,

 

 

and the fans on the FC140 are quite poweful so im not sure a 70mm fan will have much effect when one of the prisma al14s (and soon to be an AL-12 too) are pointing straight at it.

 

Temps changed a little as i removed the 2 exhaust fans  as they werent wired into each other (unlike the front ones) and were easier to get out for the new pc, but as i said the temp difference is mostly within margin of error so no issue there really

 

FC140 fan specs

 

140*27mm

 

120*25mm

[doug_locke]

7 hours ago, TatamiMatt said:

Yeah thats an old photo, the fan is attached to the front tower, this photo was taken mid swap over, also rotated its now 90degrees as the fan is actually 152x140mm outer so now sits a little lower and hits more fins and heatpipe,

 

and the fans on the FC140 are quite poweful so im not sure a 70mm fan will have much effect when one of the prisma al14s (and soon to be an AL-12 too) are pointing straight at it...

 

..Temps changed a little as i removed the 2 exhaust fans  as they werent wired into each other (unlike the front ones) and were easier to get out for the new pc, but as i said the temp difference is mostly within margin of error so no issue there really

 

You probably right about the 70mm fan, a reasonable person wouldn't bother trying it. 

General rule of thumb with axial fans , though, a fan blowing directly on a component cools the component far better than a fan pulling air away from it. 
But fans only do so much with these heatsinks, and fan blades quantity, size, pitch, cord, camber, shape, and hub size all effect the rate vacumn and exhaust pressure drops off over distance. Effects are further confounded by the radiators fin design since they add resistance but also acts as a shunt. A case fan with perpendicular and flairing blades would do a crap job cooling that heatsink straight parallel blades can create a lot more vacuum pressure. 

 

[RevGAM]

1 hour ago, doug_locke said:

You probably right about the 70mm fan, a reasonable person wouldn't bother trying it. 

General rule of thumb with axial fans , though, a fan blowing directly on a component cools the component far better than a fan pulling air away from it. 
But fans only do so much with these heatsinks, and fan blades quantity, size, pitch, cord, camber, shape, and hub size all effect the rate vacumn and exhaust pressure drops off over distance. Effects are further confounded by the radiators fin design since they add resistance but also acts as a shunt. A case fan with perpendicular and flairing blades would do a crap job cooling that heatsink straight parallel blades can create a lot more vacuum pressure. 

A couple of questions for you and @TatamiMatt.

First,  Major Hardware has tested some promising prop designs on a Noctua. Any thoughts on the best of the best?

 

Second, fan design also dictates in which direction the wind blows, and from which part of the prop. I have fans that blow out in a hollow cone,  a small number that have a filled cone, and some that push the air fairly straight. Thinking of all the uses in a PC, what is best for which functions?

[doug_locke]

On 3/28/2024 at 4:56 PM, RevGAM said:

A couple of questions for you and @TatamiMatt.

First,  Major Hardware has tested some promising prop designs on a Noctua. Any thoughts on the best of the best?

 

Second, fan design also dictates in which direction the wind blows, and from which part of the prop. I have fans that blow out in a hollow cone,  a small number that have a filled cone, and some that push the air fairly straight. Thinking of all the uses in a PC, what is best for which functions?

My knowledge about this stuff is dated, so I don't know what's best. Without rpm being a factor Noise, static pressure, vacuum pressure, and airflow are usually trade offs. 

 

I do know, as my 35+mm/H2O fan has a huge hub, three small fairly square looking blades,  is only 100cfm bt you can feel that airflow 20feet awat. 

 

 

 

[TatamiMatt]

10 hours ago, RevGAM said:

First,  Major Hardware has tested some promising prop designs on a Noctua. Any thoughts on the best of the best?

Havent seen any of that, do you have a link?

 

10 hours ago, RevGAM said:

Second, fan design also dictates in which direction the wind blows, and from which part of the prop. I have fans that blow out in a hollow cone,  a small number that have a filled cone, and some that push the air fairly straight. Thinking of all the uses in a PC, what is best for which functions?

Im assuming the least useful would be the hollow cone as you dont want a dead spot if possible, Expanding cone im assuming would have good starting static pressure but drop off quicker than and cylinder of air, as theyll experience more drag as the air spreads out. Good for radiators as they only need high static pressure over a short distance and ideally over the widest range possible to cool as many fins as possible. Finally the cylinder would keep static pressure the longest but the moving air will hit less components. So not ideal for radiators but possibly ideal for some heatsinks with heatpipes closer together like the FC140 or FS140, whereas the phantom spirits would be more spread out and would benefit slightly more from an expanding cone. A mixture of expanding cones and cylindrical air would also be good for case fans as you might want to just dump air into the case and hit as much as possible (expanding cone) or direct air, directly to a component (cylindrical air), to give examples, my lower front case fan might benefit from an expanding cone to provide air to the GPU, however the upper one might benefit from the cylindrical air to channel air straight into the cpu heatsink at a higher pressure

[doug_locke]

15 hours ago, TatamiMatt said:

Havent seen any of that, do you have a link?

 

Im assuming the least useful would be the hollow cone as you dont want a dead spot if possible, Expanding cone im assuming would have good starting static pressure but drop off quicker than and cylinder of air, as theyll experience more drag as the air spreads out. Good for radiators as they only need high static pressure over a short distance and ideally over the widest range possible to cool as many fins as possible. Finally the cylinder would keep static pressure the longest but the moving air will hit less components. So not ideal for radiators but possibly ideal for some heatsinks with heatpipes closer together like the FC140 or FS140, whereas the phantom spirits would be more spread out and would benefit slightly more from an expanding cone. A mixture of expanding cones and cylindrical air would also be good for case fans as you might want to just dump air into the case and hit as much as possible (expanding cone) or direct air, directly to a component (cylindrical air), to give examples, my lower front case fan might benefit from an expanding cone to provide air to the GPU, however the upper one might benefit from the cylindrical air to channel air straight into the cpu heatsink at a higher pressure

 

On 3/28/2024 at 4:56 PM, RevGAM said:

A couple of questions for you and @TatamiMatt.

First,  Major Hardware has tested some promising prop designs on a Noctua. Any thoughts on the best of the best?

 

Second, fan design also dictates in which direction the wind blows, and from which part of the prop. I have fans that blow out in a hollow cone,  a small number that have a filled cone, and some that push the air fairly straight. Thinking of all the uses in a PC, what is best for which functions?

I gave this a second thought, I dont think the airflow pattern alone tells much about the fan. Prop design is mostly trial and error.

Laptop fans, and heatsinks with fans mounted inside a cavity benefit from the empty ring of air because direct flow would try to go back out through the exhaust. 
The expanding cone of air is like a house fan design, it loses pressure quickly but gets air everywhere.


 

[doug_locke]

My highest pressure 120mm fan. Literally can feel it blowing 20+feet away. 

Static Pressure 35.8 mmH2O, 102 CFM, 3100rpm 14w

 

There are axial fans out there with much higher CFM (250+) I haven't come across any with higher static pressure

 

 

[freeagent]

Good luck running that off of your mobo header lol.

[RevGAM]

17 hours ago, TatamiMatt said:

Havent seen any of that, do you have a link?

I'm shocked! An airflow fan like you not knowing about this custom prop testing?

 

52 minutes ago, doug_locke said:

My highest pressure 120mm fan. Literally can feel it blowing 20+feet away. 

Static Pressure 35.8 mmH2O, 102 CFM, 3100rpm 14w

 

There are axial fans out there with much higher CFM (250+) I haven't come across any with higher static pressure

If you go to Digi-Keys, you can hunt down lots of fans with higher AF and/or SP. I have a few that meet or exceed 35 mmAq and 102 CFM. I THINK the strongest fan I have is Youngyi Science and Technology Y-Y 12038H12B Snowfan with a reported 230 CFM but I'm not sure of the SP, and the Delta 12038 (PFC1212DE-6A50), which has 253 CFM and 35.89 mmAq. Both are too powerful for my fan controllers.

[doug_locke]

15 hours ago, doug_locke said:

My highest pressure 120mm fan. Literally can feel it blowing 20+feet away. 

Static Pressure 35.8 mmH2O, 102 CFM, 3100rpm 14w

 

There are axial fans out there with much higher CFM (250+) I haven't come across any with higher static pressure

 

 

This is an AC fan so it would just be plugged into the wall and controlled with a 50¢ dimmer switch.

 

The DC version uses a little more than power (12v x 1.66amp) still way less than a Mobo header.

 

I'm sure it would vibrate the Mobo/heatsink too much as a heatsink fan.

[doug_locke]

14 hours ago, RevGAM said:

I'm shocked! An airflow fan like you not knowing about this custom prop testing?

 

If you go to Digi-Keys, you can hunt down lots of fans with higher AF and/or SP. I have a few that meet or exceed 35 mmAq and 102 CFM. I THINK the strongest fan I have is Youngyi Science and Technology Y-Y 12038H12B Snowfan with a reported 230 CFM but I'm not sure of the SP, and the Delta 12038 (PFC1212DE-6A50), which has 253 CFM and 35.89 mmAq. Both are too powerful for my fan controllers.

I have one if those Delta fans, use 4amps (about 50watts) and 67db... That's 16-17 TIMES louder than a 20db fan, 10 times louder than a 40db fan (which is already very loud).

[doug_locke]

Today's experiment: Added an 80mm center top exhaust fan and mounted and angled baffle to keep it from drawing air away from the cpu intake fan. In theory the smaller fan + baffle shouldn't interfere with the cpu cooler intake fan like a center 120mm exhaust fan does. Baffle keeps the air from the top-front intake fan from being immediately sucked out by the exhaust fan. And mounting the 80mm fan on the left (over the mobo) "should" pull air towards the mobo before expelling it, should cool ram and the top vrms slightly better.

 

 

Top down diagram: