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CPU Fan -- Is Bigger Better?

S

Sarobi

Member
I'm using an SLK 900A heaatsink. Recently someone said a smaller fan like a 70mm TMD (YS Tech ) would be better than a 92mm w significantly more CFM. The thinking is that the smaller fan pushes more air through to the center of the heatsink while the larger one wastes lots of air over the sides of the fins and has a larger dead zone in the center due to size mismatch between fan and heatsink. Do you guys agree? Can a smaller and lower CFM fan be more effective than the larger ones?

Use this link to see the description of the TMD Fan: tmdfan

 
yes and no... It is true that the hub of a TMD 70mm fan is much smaller than the hub of the 92mm fan, thus allowing more air to reach the center of the heatsink. However, a 70mm fan pushes far less air than the 92mm, so the increase in air reaching the center doesn't make a difference if less air total is reaching the heatsink and at slower speeds (I'm assuming... if you're using a low-speed 92mm fan, they're probably around the same). I would think raw CFM would overpower the slight increase in efficiency.
 
Yeah, I don't know what the break-even point would be in order to weigh one benefit against the other. What if I used one of those Zalman fan arms (bracket) to elevate a larger fan slightly above the heatsink instead of attaching the fan directly? Do you think that would eliminate the dead spot in the center? I could probably even put in a 120mm fan using the bracket which would help cool the NB a little too if angled the right way (the bracket lets you position the fan in different ways -- also hold more than one fan). Would that work, or do you think it would be pointless?

Edit: The 120mm Evercool Aluminum fan can push over 84 CFM at only 31db --- I'd probably use that one
 
When you suspend the fan above the heatsink, the air will tend to blow around the heatsink more instead of through it, reducing its effectiveness. This effect would be even more pronounced with your SLK900a that has very thin gaps between fins. A heatsink with a more open design such as a Swiftech or Alpha might do better than the Thermalright if they are cooled with a suspended fan.

I'd go with a decent 92mm fan for quietness. A Panaflo L1a should do a great job.
 
Yes, that makes sense, especially regarding the thin gaps on the 900a. I also agree that the Panaflow would be a good solution -- just wish it could be more visually interesting inside my window case. Main thing right now though is to have sufficient cooling without my wife thinking I've installed a landing strip in the spare bedroom 😀
 
To tell you the truth, I doubt reducing the dead spot would even have any noticeable effects. It's probably best to just stick with a Panaflo L1A, or even an adjustable fan (I have one for my CPU, on High for gaming, on Low when I go to sleep) which are very zooty.
 
Yeah, zooty. What. You never heard of zooty?
I'd say go with the 92. I have a 92mm Vantec Stealth on my 900A and it's very quiet and effective.
 
I can't tell you how happy I've been with the Vantec Aeroflow, using the same YS TMD fan. It's quiet as a mouse, and more efficient than the 7k RPM jet-engine HSF combo (Thermaltake Volcano 6cu+) I had in there previously. Also, the heatsink design on the AeroFlow is $$. For $26, you can get them together.

So as far as the fan goes, I love it. Check out Vantec's heatsink though too, quite a combo.

 
My SLK-900A is happily cooling my 1700+ @ 200x10.5 @ 1.75Vcore (bios) (adjust accordingly for Abits reducion in voltages) at 46C load and an 80mm Panaflo L1A.

I cant seem to find my 92mm fan clips and the ones I was shipped to replace them are 80mm... fits my 80mm snugly.
 
zooty
Pronunciation: 'zü-tE
Function: adjective
Date: 1946
: typical of a zoot-suiter : flashy in manner or style <a zooty haircut>
 
If you can get ahold of the fan they use on the Thermaltake Silent Boost then that's what I recommend. It's supe quiet, made by Panasonic and pushes a decent amount of air, 30 CFMs.
 
The bigger the more the CFM and the silent it would be, but in a heatsink you should also keep in mind the air pressure of the fan, luck
 
if you want visually interesting get some coolermaster uv led fans. they are quiet to boot. if you want them to force air through those thing gaps better. stack two with a hollowed out fan between them. better at fighting back pressure🙂
 
Originally posted by: 0roo0roo
if you want visually interesting get some coolermaster uv led fans. they are quiet to boot. if you want them to force air through those thing gaps better. stack two with a hollowed out fan between them. better at fighting back pressure🙂
Click to expand...

sounds dangerous!!! bring it on :beer:
 
Originally posted by: Noubourne
I can't tell you how happy I've been with the Vantec Aeroflow, using the same YS TMD fan. It's quiet as a mouse, and more efficient than the 7k RPM jet-engine HSF combo (Thermaltake Volcano 6cu+) I had in there previously. Also, the heatsink design on the AeroFlow is $$. For $26, you can get them together.

So as far as the fan goes, I love it. Check out Vantec's heatsink though too, quite a combo.
Click to expand...

I have the same HSF and I love it compared to the Volcano 9 I did have. It even keeps my 2400+ about 4C cooler than the V9 too.
 
Originally posted by: Sarobi
Yeah, I don't know what the break-even point would be in order to weigh one benefit against the other. What if I used one of those Zalman fan arms (bracket) to elevate a larger fan slightly above the heatsink instead of attaching the fan directly? Do you think that would eliminate the dead spot in the center? I could probably even put in a 120mm fan using the bracket which would help cool the NB a little too if angled the right way (the bracket lets you position the fan in different ways -- also hold more than one fan). Would that work, or do you think it would be pointless?

Edit: The 120mm Evercool Aluminum fan can push over 84 CFM at only 31db --- I'd probably use that one
Click to expand...

I have had the 120mm Evercool Fan. The 31db is very very very annoying. I cannot recommeding buying it, its all marketing hype. Its a nice looking fan, but the noise at Medium or High settings on a rheostat is horrific. Hope this helps!
 
yea, 31db is bad. 20db fans aren't exactly totally silent yet, so 31 is err not good. sometimes specs are a tad inaccurate😛 31db where? measured from 20ft? 😉
 
Originally posted by: NokiaDude
If you can get ahold of the fan they use on the Thermaltake Silent Boost then that's what I recommend. It's supe quiet, made by Panasonic and pushes a decent amount of air, 30 CFMs.
Click to expand...
Panaflo M1A, IIRC. A M1A or L1A will do great, and far better than most fans trying to force air between those fins.
If you look at the design of the SLK heatsinks, you might notice that they use the center for extra mass. Maybe not having a dead spot could help, but not that much.
 
well those slks also have no base under most of the fins, allowing air to flow straight through more easily🙂 great design, esp for low rpm fans.
 
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