Vertical HSF is it a bad design?

[Peroxyde]

Hi,

I bought a Arctic Cooling Freezer Pro Rev.2
http://www.arctic-cooling.com/catalog/product_info.php?cPath=1_42&mID=304

This is for another computer. And got exactly the SAME problem than when I did it for the first computer. The fan is now vertical and there is no more downwash air flow. As a result, the chipset and VRM modules got heated.

From my little experience, this type of vertical HSF is rather problematic. Why are they designed that way?

 

[God Mode]

Because in some situations, blowing the hot air from the CPU out the rear/top exhaust is better than recirculating it inside the case. There are compromises you make. A fan pointed somewhere towards the vrm/northbridge area works well.

 

[Peroxyde]

There are compromises you make. A fan pointed somewhere towards the vrm/northbridge area works well.

I assume you meant an extra fan where you need to come up with a creative way for the mounting?

 

[acole1]

IMHO the flow of the air from the front of the case to the back should be enough. If not, you may need a new case.

 

[Peroxyde]

IMHO the flow of the air from the front of the case to the back should be enough. If not, you may need a new case.

Seems not enough, in my 1st computer, the case is Antec Designer. After I changed for the vertical HSF, the chipset heated and I had errors in DVD Writer. Granted the board is Asus P5NA7-VM with a nVidia chipset with integrated geforce 9300 which probably heated more. In anyways, I had put a 120 mm fan on top of the chipset, attached by some improvised garden wires and the issue was fixed.

What I am surprised now is that the 2nd computer, doesn't have integrated graphic, but still suffers the same issue. And tjhis time it's the VRM components around the CPU.

 

[frostedflakes]

They tend to allow for bigger heatsinks, and as mentioned the airflow works with the front-to-back flow that most cases have, whereas downward blowing heatsinks "disrupt" it (for lack of a better word). Higher VRM and northbridge temps are a downside, but a lot of enthusiast boards these days come with pretty bulky heatsinks on the chipset and CPU power circuitry, so this isn't always an issue.

 

[Zap]

You can get much better cooling for the CPU with the "tower" style heatsink, at the expense of chipset/VRM temperatures. It is a tradeoff that some are willing to make.

 

[Modelworks]

My biggest concern with large heat sink is how they can stress the motherboard. I have seen more than one board warped and ruined by a heavy heat sink hanging on to it. When I build a pc now I always check how much the heatsink weight is bending the board. I then attach a nylon tie just tight enough to the case to take off some of the strain.

I do the same thing with video cards too. Lately a lot of card with large heatsinks will cause a card to bend the further it gets from the slot. Most cards already have a hole there where you can attach a nylon tie strap and pull the card up a bit to support some of the weight.

 

[Peroxyde]

Would a back plate (in the shape of an X) that allows you to screw the heat sink on relieves the stress?

And BTW, what do you estimate the "critical" weight beyond which the heat sink will warp the motherboard?

 

[Modelworks]

Would a back plate (in the shape of an X) that allows you to screw the heat sink on relieves the stress?

And BTW, what do you estimate the "critical" weight beyond which the heat sink will warp the motherboard?

The back plate can relieve some of the stress but not all of it because it is still only making contact with 4 points on the board.

Critical weight is a hard thing to say. I usually install the heatsink on the board before it is installed in the case then hold the board vertical like it will be in the case and with a free hand lift the heatsink up vertical just a bit to see how much downward force it is putting on the board. It isn't always weight , sometimes it is how tall the heatsink is . The taller it is the more it will stress the board. It usually doesn't take much to stop the flexing of the board. A single support pulling towards the top of the case with maybe a 1/4 lb of force can stop the flexing. The same goes for video cards. Attaching a single tie to the far corner, usually near the power connector, again tied to the top of the case can help insure the card will last a long time. They really flex when heated and I suspect is why some cards develop memory issues.

 

[Peroxyde]

Hum ... I may have found a cheap compromise. Detach the fan and let it rest on the bottom of the board, so that a small portion of the fan blow under the heat sink where the VRM components are located. Luckily in my case, the chipset heat sink also catches some air from that contraption.

Then attach the fan to the heat sink by flexible / plastic coated phone wires. The heatsink is slightly warmer by +3 degrees C but the heat around the VRM components is now gone.

 

[frostedflakes]

You could also attach the fan normally, and then use something (piece of cardboard, for example) at the exit of the heatsink to direct some of the airflow down toward the VRM. On my Freezer 64 a few of the fins were bent downward for this purpose. This picture shows what's going on.

No idea why they didn't do this on the Freezer 7, I'm sure it would help a bit with VRM cooling.