I'm about to buy 20 of these heatsinks for the 20 cob fixture, or shouldn't I?

Strike that last statement^^ just remembered, I did a 'spider cob' conversion that used just those type of components and it is more than happy effectively cooling 40w cob's. I doubt the extra 10w would severely hinder it.
thanks my man.

btw. can you or someone else tell me if a "heavier" heatsink is most likely a better one since it will absorb more heat?
 

Trippyness

Well-Known Member
thanks for your replies, I'm learning a lot from them.

The problem is however that I can not buy 1 at that price from this company.
I can buy a minimum of 40 @ $1.5 each (overstock). Besides, I can't return them.
To make it even harder: I can only get this insane bargain today because the guy I know in this company will be gone for 4 weeks starting tomorrow. He will buy these on his own name from his job, thats why the price is low.
May I ask where you are finding heatsinks for 1.5?
Would love to check out this source.
 

furalle

Active Member
Awesome value I want some too :=)

I think you use that 0.357 oC/W this way:
Heatwatts=aprox 60% of 50W=30W
then 0.357x30+roomtemp(25)=35,71 Heatsink temp
 

Nugachino

Well-Known Member
While a bigger heat sink potentially has more cooling capacity. I do believe it's actual surface area and relative airflow that dictates how effective a cooler really is.

Also. If you're going passive cooling. Choose a cooler that will allow for natural thermal convection. One where the air can come in from the sides and vent upwards with as little restriction as possible.
 

Nugachino

Well-Known Member
Awesome value I want some too :=)

I think you use that 0.357 oC/W this way:
Heatwatts=aprox 60% of 50W=30W
then 0.357x30+roomtemp(25)=35,71 Heatsink temp
I'm glad you can numbers. Because that shit looks like Cantonese to me... Not that I'd know Cantonese if I saw it.
 
May I ask where you are finding heatsinks for 1.5?
Would love to check out this source.
$1.5 price is just for me as we're long time friends, besides this is old stock just sitting in the warehouse only sporadically being sold for around $9 each.
If you are interested in some, message me and I will check if I can make a deal for you. I can pick them up myself and ship them, the only problem is that I'm in the Netherlands so shipping to USA will probably be costly.

Awesome value I want some too :=)

I think you use that 0.357 oC/W this way:
Heatwatts=aprox 60% of 50W=30W
then 0.357x30+roomtemp(25)=35,71 Heatsink temp
Hi ! Thanks for your calculations:) Like I told Trippyness, if you want some shoot me a message.

While a bigger heat sink potentially has more cooling capacity. I do believe it's actual surface area and relative airflow that dictates how effective a cooler really is.

Also. If you're going passive cooling. Choose a cooler that will allow for natural thermal convection. One where the air can come in from the sides and vent upwards with as little restriction as possible.
Ah, like a pin heatsink?
 

furalle

Active Member
While a bigger heat sink potentially has more cooling capacity. I do believe it's actual surface area and relative airflow that dictates how effective a cooler really is.

Also. If you're going passive cooling. Choose a cooler that will allow for natural thermal convection. One where the air can come in from the sides and vent upwards with as little restriction as possible.
Yes there is heat dissipation and there is heatstorage capacity. Much mass equals lots of heatstorage capacity but it also has to transfer from heatsink to air. Heat travels upwards so one has to think about that in design.
 

Nugachino

Well-Known Member
Pin sinks are exactly what I'm on about. They've got quite a large surface area. Which is what makes them so effective. Even more so if you can add a little air circulation to the mix.
 
Pin sinks are exactly what I'm on about. They've got quite a large surface area. Which is what makes them so effective. Even more so if you can add a little air circulation to the mix.
I understand your logic, but then again.. in my situation I only run my cobs at 1400a/50w so I don't need the best coolers.
Besides, a pin heatsink is like atleast $15-$20 each, while the heatsinks which I mentioned in the opening post are only $1.50 each including fan
 

Abiqua

Well-Known Member
While a bigger heat sink potentially has more cooling capacity. I do believe it's actual surface area and relative airflow that dictates how effective a cooler really is.

Also. If you're going passive cooling. Choose a cooler that will allow for natural thermal convection. One where the air can come in from the sides and vent upwards with as little restriction as possible.
mass
 

Abiqua

Well-Known Member
@Strainhunters

I wouldn't mess around with these, did you look at the actual mounting area of the heatsink? There is no way a chip will fit on those. I would pass, hard.

Just get some Mechatronix actives. The Alpine 11+ are great because they are about 400 grams of metal. That's what helps them cool.

You can have as many fancy designs as you want, but without mass, there will be no cooling....

Anyone need any cool charts to see what I mean. I can confuse this entire thread in an instant :)
 
@Strainhunters

I wouldn't mess around with these, did you look at the actual mounting area of the heatsink? There is no way a chip will fit on those. I would pass, hard.

Just get some Mechatronix actives. The Alpine 11+ are great because they are about 400 grams of metal. That's what helps them cool.

You can have as many fancy designs as you want, but without mass, there will be no cooling....

Anyone need any cool charts to see what I mean. I can confuse this entire thread in an instant :)
The mounting area is 2.8cm, which I checked, will fit my Citizen 1212 cob's.

Now, mass, thats another story. These units weigh around 190 grams (avg weight from different sites), but seem to be able to cool CPU's without too many issues. I think the design for these is to dissipate heat fast instead of absorbing a big part of it first..

The price of $1.5 seems like it's worth the try tho...hmmm... Wish there was someone with 'hard' facts to convince my old ass not to buy these :P

edit: I appreciate your reply tho! Can you elaborate a bit about your theory?
 

Ganjineer

Member
When CPU manufacturers release their chip specifications they include a metric called "thermal design power" (TDP). https://en.wikipedia.org/wiki/Thermal_design_power

TDP is the maximum amount of heat given off by the CPU (under real world usage). Although TDP is not exactly equal to the power consumption of the processor, it is an extremely close approximation and is frequently used in the industry to estimate power consumption of a chip. So, given this information, when a heat sink manufacturers state that their coolers are rated for "95W CPUs" they are in fact referring to the TDP and, to a lesser degree, power consumption of the processor. Additionally, properly designed heat sinks will be able to safely cool CPUs running at peak TDP full-time.

If you plan on running your CLU048-1212's at 50W power consumption then ~20-30W will be dissipated as heat and need to be removed by your heat sink. Given that the manufacturer says that the heat sinks are rated for 95W TDP they should have no trouble cooling a chip giving off ~20-30W of heat to acceptable operating temperatures. Those heat sinks seem like an economical solution to your problem. Go for it!
 

furalle

Active Member
Btw has anyone here tried to solder on the cob on heatsink? I know CPU manufactors solder the ihs on cpus sometimes. Would be neat to just solder them on without any holes and tapping. When chip dies just heat it up and remove.
 

Nugachino

Well-Known Member
I don't know about solder. But you could probably use some high range thermal glue... if you didn't want to change the parts again.
 

furalle

Active Member
I don't know about solder. But you could probably use some high range thermal glue... if you didn't want to change the parts again.
I did some research and it seem pretty easy to solder. Just need a hot heatgun or a torch and melt a ball of solder on a non oxidated surface where you want chip. Them just add the chip with fluss on it. A non acid type fluss so one doesnt melt the electronics :)

Should make a great connection for heat transfer.
 
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