Cpu C/W

[camplo]

I can't find any information about the thermal resistance of the cpu chip itself. Anyone have a clue what it is?


If anyone can answer this question to save another thread here it is. I see coolers advertise that they offer 300watts of cooling power? that makes no sense to me. What the hell is 300 watts of cooling power. 300watts does no = a certain amount of heat....does it? If so....how much.....sounds like you would need to know the thermal resistance of whatever the 300 watts is going through.......and if its a cpu.....how much thermal resistance is there?

 

[4745454b]

CPUs are measured at the rate in which they emit heat. 77W or 125W. The coolers are also listed at the max heat they can handle. Stock coolers can usually only handle the heat of the CPU itself. If you buy a 125W CPU, odds are the stock cooler can handle 125W or 150W. If you OC, then you will usually exceed the 125W thermal envelope.

There is no math to do. You don't need to know the resistance of the chip or anything like that.

 

[steddora]

4745454b is correct to a point. Take my 2600k Sandy Bridge processor for example.

It has a maximum TDP. Well what exactly is TDP?

TDP is an acronym for "Thermal Design Power".

Now the rating on a processor is different from the rating on a heatsink. The TDP is a determination of how much power the CPU will actually use at "full load". Which my 2600k runs at about 92w (Rated by CPUID Hardware Monitor) at 100% load. At 4.4Ghz however it will use 122w which is quite a bit over the stock 95w rating.

Now that we know what that does, what does it mean for a heatsink?

For a heatsink, let's take your 300w example into play. Effectively that heatsink is rated to cool a processor that uses approximately 300w of power. Now that's a TON of power flowing through any processor. So technically that heatsink would be extremely overkill.

There is a catch though. Not all CPU's are the same. My E8400 dual core that ran 65w ran hotter on my Zalman 9500A than my 2600k processor did with four cores. So this rating isn't completely accurate. There's many different variables that go into play with the wattage ratings on heatsinks and CPU's. But general guidelines are that a 95w cooler should be able to cool a 95w processor.

 

[camplo]

Does anyone know where to get heatsinks for various applications here in America?Everything I find is in china....



an even better question, if I am just going off of wattage along for the heat source. How do I use the wattage to determined how big a heat sink needs to be?

 

[4745454b]

Not sure I'd say correct to a point as much as correct without trying to make things complicated. We could get into a discussion about thermals and die size as well, but I'm not sure what good it will do.

On a related note I'm not sure why the OP is asking. What are you trying to do? Why to buy heatsinks in the USA? Uhm, Newegg? I think some background info would be great as I'm not sure why you are asking what you are.

 

[camplo]

I need to cool 500watts of heat dissipation to like 15 above ambient, passively. Is this possible? I don't want to have to order a heatsink from china and pay a whole bunch in shipping. But it might not be as expensive as I was told by word of mouth.

 

[4745454b]

No single PC cooler that I know, but I get the feeling we aren't talking PC here. Water loop if you need to remove that much heat. Will probably require a custom block.