Aluminium Case Acts As A Massive Heatsink

ez2remember · Post by **ez2remember** » Sat Dec 07, 2002 9:01 pm

Ahh, I just had a wonderful idea that has come to my head, I think it might just work.

This would work best for those who own aluminium cases. I wonder if taking of the lid of the PSU and removing the heatsinks from it. Then making a custom heatsink large enough or using a heatpipe that is in direct contact with the top of your case, it would conduct heat to the case itself. This would act as the biggest heatsink there is and will be cooled because the case is fairly cool from external ambient tempertures. This may also apply to the CPU, but it is harder to get this in contact with the case, a heat pipe might work best for this solution, like the ones found on the new shuttle PC's.

Do you think this will work?

I mean if it does, then the amount of fan cooling will be absolutely minimal. There maybe virbrations but it is far easier to dampen down the noise than a fan.

powergyoza · Post by **powergyoza** » Sat Dec 07, 2002 9:15 pm

Yeah, it's a neat idea. Someone from Japan beat you to the punch though. Here's the link: http://www.geocities.jp/numano3

ez2remember · Post by **ez2remember** » Sat Dec 07, 2002 9:19 pm

This may even work without removing the PSU heatsink, depending on the model. If you can secure it somehow tightly to the top of your case where the heatsink actually is incontact with the case. Maybe some Artic Silver 3 or AS adhesive could be applied for good contact to the case.

ez2remember · Post by **ez2remember** » Sat Dec 07, 2002 9:29 pm

powergyoza wrote:Yeah, it's a neat idea. Someone from Japan beat you to the punch though. Here's the link: http://www.geocities.jp/numano3

This seems to be done for the CPU, not the PSU. Seems complex to me, and doing it to the PSU would be so much easier and which I find more annoying as sound is clearly comming out from the back of the PSU.

Red Dawn · Post by **Red Dawn** » Sat Dec 07, 2002 10:21 pm

Providing a direct link from the heatsinks in the PSU to the chassis may not be the best of ideas, since the heatsinks are live (or so I've been told by people that have tried to find out for themselves

). So in effect, you'd get 'zapped' everytime you tried to touch the aluminium frame, in case I didn't totally miss one of your main points of arguement... it's way past my bedtime, so to speak, so please forgive me if I did.

Post by **MikeC** » Sat Dec 07, 2002 10:38 pm

since the heatsinks are live

Some are, some aren't. You can find out without zapping yourself by attaching the ground lead from a multimeter to ground (any black DC output lead), setting the multimeter on a high VDC scale, then touching the heatsink momentarily with the red (+) probe -- while the PSU is running. If you get a voltage reading you know the HS are live. Some PUSs actually tell you whether the HS are live with a sticker on the outside.

larrymoencurly · Post by **larrymoencurly** » Sun Dec 08, 2002 1:19 am

larrymoencurly · Post by **larrymoencurly** » Sun Dec 08, 2002 1:21 am

I measured 170 volts DC on one of the heatsinks of each of these PSUs:

300W Delta DP-300BP
300W Antec Smartpower
300W Powmax 6100B

The circuit board would have to be cut to eliminate this, and in a least one PSU this would make the copper trace so narrow that a thick jumper wire might have to be added.

This PSU measured 0V on both heatsinks:

300W Maxpower PX-300W (piece o' junk)

Even if the heatsink is at 0V, do you really want it touching the case when it has high voltage transistors bolted to it that are insulated by just thin sheets silicone rubber? What if one of those sheets gets pierced by pressure between the transistor and heatsink?

quokked · Post by **quokked** » Sun Dec 08, 2002 6:37 am

[quote="Red Dawn"]Providing a direct link from the heatsinks in the PSU to the chassis may not be the best of ideas, since the heatsinks are live (or so I've been told by people that have tried to find out for themselves

). So in effect, you'd get 'zapped' everytime you tried to touch the aluminium frame, [quote]

ultimate case security system NO ONE will dare mess with your cooling setup and your internals if u have this rigged up

Red Dawn · Post by **Red Dawn** » Sun Dec 08, 2002 6:51 am

I was aware that one of the heatsinks normally aren't live MikeC, but I have to admit I didn't know there were PSU's without live heatsinks, thanks for the heads-up larrymoencurly! Regardless of which though, as I saw it he was going to rig it up so that both heatsinks were connected, which would produce the behaviour forementioned in my earlier post.

quokked wrote:ultimate case security system NO ONE will dare mess with your cooling setup and your internals if u have this rigged up

Haha, yes, and yourself included most likely.

ez2remember · Post by **ez2remember** » Sun Dec 08, 2002 8:29 am

MikeC wrote:
since the heatsinks are live
Some are, some aren't. You can find out without zapping yourself by attaching the ground lead from a multimeter to ground (any black DC output lead), setting the multimeter on a high VDC scale, then touching the heatsink momentarily with the red (+) probe -- while the PSU is running. If you get a voltage reading you know the HS are live. Some PUSs actually tell you whether the HS are live with a sticker on the outside.

Hey,

Can anyone tell me any PSU HS that is not live?

I want to buy one, thanks for the advice guys you have been very helpful.

larrymoencurly · Post by **larrymoencurly** » Sun Dec 08, 2002 12:48 pm

I've got to repeat this: Even if the heatsinks have zero voltage on them, you don't want to connect the one with the high voltage transistors on it to the computer case because you can't trust the insulation on those transistors 100%.

By the way, when you measure the voltage on the heatsinks, be sure to set the meter to DC because it'll read 0V on the AC scale, no matter how high the voltage is. You should also unplug the power supply from the AC, wait a while, and then check the heatsinks again with the meter set to ohms, and connect the meter leads both ways because a diode can block the current flow one way. Don't just measure between the heatsink and the power supply case but also between the heatsink and a black wire on one of the power connectors (like a disk drive connector).

TerryW · Post by **TerryW** » Tue Dec 10, 2002 9:56 pm

Hi all.

I concur with larrymoencurly: the insulation of the transitor devices cannot be counted on for high-voltage isolation.

In some instances, power transistors are internally connected from one lead connection to the case of the transistor (the case offers some heatsinking capabilities and provides better heat conductance to larger HS).

This is the reason for having a mica insulation between the transistor & the HS, and also a fibre washer under the screw head. These isolate the transistor to the HS.

If the PSU manufacturer intended to ground the HS to the case, I think they would have. Any fault currents would have been shunted to earth ground (chassis), possibly blow the PSU but the user would not be harmed.

My 2-bits worth!

TerryW

counterpt · Post by **counterpt** » Sun Mar 02, 2003 6:40 am

Red Dawn wrote:Providing a direct link from the heatsinks in the PSU to the chassis may not be the best of ideas, since the heatsinks are live (or so I've been told by people that have tried to find out for themselves ). So in effect, you'd get 'zapped' everytime you tried to touch the aluminium frame, in case I didn't totally miss one of your main points of arguement... it's way past my bedtime, so to speak, so please forgive me if I did.

I don't think aluminum is an electrical conductor.

1HandClapping · Post by **1HandClapping** » Sun Mar 02, 2003 10:05 am

counterpt wrote:I don't think aluminum is an electrical conductor.

Aluminum is an excelent conductor of both heat and electricity, though not as good as copper. Aluminum is too brittle to make durable wiring, though in the 1960's it is was used in place of copper in home wiring when there was a copper shortage.

Gandalf · Post by **Gandalf** » Sun Mar 02, 2003 10:25 am

All the electrical difficulties put aside, I think it's a nice idea if you want to turn the top of your case into a mini-stove. I would love to bake my eggs on it in the morning! (not being sarcastic actually)

counterpt · Post by **counterpt** » Sun Mar 02, 2003 12:49 pm

oops