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Larger Heatsink or Large Fan: Which is better?

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Nagorak

Senior Member
Joined
Dec 19, 2000
Ok obviously when we are cooling a CPU we try to get the largest fan, with the largest and highest output fan possible. But when we're trying to cool our video card's GPU, we can't really take the largest heatsink and the largest fan possible, at least not unless we want to block all of our PCI slots.

I'm trying to cool my Radeon GPU, but I can only afford to lose a single PCI slot (stuff is in all the others). Right now I have attached a rather large heatsink (from a graphics standpoint) cut from an old Slot 1 CoolerMaster. I'd say the heatsink is about 15mm tall, with a 10mm fan attached. At a combined size of 25mms this HSF combo just barely fits with some extra air flow room between it and the 2nd PCI card.

Now, the question here is, the fan only moves something like 10 cfm of air. Is it better to have this rather large 15mm heatsink, and a fan moving 10 cfm of air, or do you think it would be better to get a smaller 5mm heatsink and a 20mm thick fan which can move 19 cfm of air? I can really see both sides of this argument, actually, since a larger heatsink exposes more heat to be removed by the fan, but a larger fan can blow away more heat.

I'm not sure I'll change my cooler in any case, but I was just wondering what you guys think. Which is better, more air, or more metal?

(P.S. if I could spare the next PCI slot too, I'd just put a 15 mm tall * 60 mm heatsink and a 60*10mm Delta fan on it ;-) )
 

Valafar

Registered
Joined
Mar 10, 2001
Location
Hemet CA
I have a Geforce 256 DDR and it gets pretty hot too. What I did was leave the original HS on and take the fan off. I then put an old fan from a Celery on it and the temps have dropped to where I can touch the back side of the card and not burn my finger. I also added a 120 mm fan blowing in from the side.
I am a fan of bigger fans (no pun intended). I figure if there is not enough air to blow or suck the heat off the HS, then a big HS is is not able to perform optimally. These are just my thoughts.
 

batboy

Senior Moment
Joined
Jan 12, 2001
Location
Kansas, USA
Maybe I'm wrong, but if you have good case ventilation, I'd think that a bigger heatsink and a smaller fan is a good compromise. Many motherboards have a sink on the northbridge with no fan, my MX video card had a GPU sink with no fan. Obviously, adding a fan works better and adding a BIG fan works best (if you have the room).
 

klosters64a

Senior Member
Joined
Dec 17, 2000
Location
Seattle, Wa
In my less than universal experience, I found that a heatsink that was OK for an original PPGA Celeron just couldn't do the job properly on a P3E. Even with a Delta 38. I guess that hurricanes are all well and good on processor HSF's, but they just can't do their job without enough metal to transfer heat away from the CPU fast enough.
 

batboy

Senior Moment
Joined
Jan 12, 2001
Location
Kansas, USA
Well said Klosters...it's all about the surface area of the heatsink. A small sink with little fins can't possibly cool better than a large sink with big fins.
 

Hoot

Inactive Moderator
Joined
Feb 13, 2001
Location
Twin Cities
If you have an axial fan right up against the next PCI card, or even real close, you will not get the fans rated CFM. Fans are reated by the manufacturer hanging in the clear with no obstructions and no resistance to airflow. I'd get a bigger fan and go to the local electronics surplus warehouse and dig through the heatsinks. I found a box of little copper pin fin ones that would be perfect for your situation. Copper will net you almost double the thermal conductivity of aluminum.

Hoot
 

markedmundb

Senior Member
Joined
Dec 18, 2000
Location
Kent, UK
Fatter Sinks are better than fatter fans.

The reason: There's more area for the heat to be transfered.

If your board was anything like mine, then you'd have an AMR slot PCI-side of the AGP slot= No problem with extruding sinks or fans.

BTW if that was my MX, then I'd get a BlOrb, spray it matt black, lap it and use Silver goop. Recommended this course of action to a mate, managed to get his core to 210Mhz.
 
W

William

Guest
there was somesite that had a thing about a video card fan cooler that didn't take up a slot. Basicly, you drill two holes to match the fan you are mounting in one of those metal slot holders. You bend it so that it will will above the card like this(sorry but hope you get idea)
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So just put your fan in the groove and sit it above the card and you will see a huge airflow increase!!!!! And it is cheap and easy to do. Allow you to keep that nice big heatsink on there with a nice big fan.