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Discussion Starter · #1 ·
Alright, so I am quite stumbled by this question.

My Intel CPU (i7 4770k) at stock speeds has a 84w TDP.

My GPUs (I have 2 780TIs) have a 250w TDP. Triple the processor!

Now my question is, why do the processors still run hotter than the GPUs. (Especially under water) The GPUs struggle to touch 60C while the CPU blinks and is at 60C hitting 70C at its highest point. I am just curious as to why these GPUs can run so much cooler but have triple the heat output!

My thought was that the die sizes are much different.... And that the processor has an IHS which is just inefficient.

I wonder if intel can start working on true enthusiast chips without and IHS
rolleyes.gif
 

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Quote:
Originally Posted by BoatOnGoat View Post

Alright, so I am quite stumbled by this question.

My Intel CPU (i7 4770k) at stock speeds has a 84w TDP.

My GPUs (I have 2 780TIs) have a 250w TDP. Triple the processor!

Now my question is, why do the processors still run hotter than the GPUs. (Especially under water) The GPUs struggle to touch 60C while the CPU blinks and is at 60C hitting 70C at its highest point. I am just curious as to why these GPUs can run so much cooler but have triple the heat output!

My thought was that the die sizes are much different.... And that the processor has an IHS which is just inefficient.

I wonder if intel can start working on true enthusiast chips without and IHS
rolleyes.gif
In a nutshell, GPUs (especially the 780TI) are massive chips, and the heat they produce comes from every part of the die.

CPUs are relatively small (maybe 1/2 the size of a GPU), and most of the heat comes from the cores, which only take up a fraction of the CPU die (maybe 1/3).

So GPUs run relatively "cool" because they heat they produce is spread out over a large area, making it easier for a heatsink to carry away. CPUs are hotter because the heat comes from a small point, which also explains why AMD's much larger, higher power CPU cores or Intel's larger, lower frequency HEDT/server CPUs tend to run cooler than your 4770k despite their higher power draw, or why the 3770k is hotter than the 2600k even though they're very similar.

The IHS/TIM also plays a role, but it's certainly not everything.
 

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Discussion Starter · #3 ·
I don't see an issue why the just don't increase the size of a CPU a little for better thermals and then you can easily push the chips a little further due to better thermals... I suppose there'd be a complicated answer for this too!
thumb.gif


Thanks for the answer, just as I expected.
 

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Quote:
Originally Posted by BoatOnGoat View Post

I don't see an issue why the just don't increase the size of a CPU a little for better thermals and then you can easily push the chips a little further due to better thermals... I suppose there'd be a complicated answer for this too!
thumb.gif


Thanks for the answer, just as I expected.
Because bigger = more expensive
tongue.gif


The 2600k is basically a bigger 3770k, if you want to look at it that way.

The benefits of die shrinks (more transistors in a given area, lower overall power consumption, faster transistor switching) generally outweigh the cons, but the increasing heat density of CPUs is a well-known problem. You can avoid it by making wider, slower, bigger cores, but neither AMD nor Intel have done that in a few years. It didn't happen with AMD because Bulldozer didn't really pan out (they already have plans for a new core in 2016), and quite frankly Intel doesn't care about overclockable mid-range desktop CPUs... Their cores work well for servers and laptops, which is where all the money is.
 

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The 780ti power consumption is 260-290w the 250w is related to the input cables which are rated.
75w-pcie
75w-6pines
150w-8pines
150w-6+6Pines
Quote:
Originally Posted by twerk View Post

TDP means the maximum amount of heat that is expected to be generated from this component. It's a ballpark estimate of the highest amount of heat that could, under reasonable circumstances, be released from a component. So please, let's not assume that a 95 watt TDP CPU will use 95 watts. When Intel says a chip has a 95 watt TDP, they certify that at the max stock turbo frequency of the CPU. The 2500k turbos up to 3.7GHZ, and Intel is saying that that CPU needs a cooler capable of moving 95 joules of heat away every second. (Also, for reference, a watt = 1 Joule per second).

R9 290X TDP is 290W, the actual stock power consumption is a few watts lower.
780 Ti TDP is 250W, the actual power consumption at stock is actually around 260W.
The i7-4790K TDP is 88W, the actual stock power consumption is closer to 80W.
etc...

Without isolating the power supplying the 750 Ti, which is very difficult because power is also drawn through the PCIe slot, it's impossible to measure power draw. Software readings are inaccurate. The closest you could get is by buying a power meter (something like a Kill A Watt) and measuring your system without the GPU installed, when you have a graphics card in you can subtract the difference. This still isn't 100% accurate as there are a lot of variables unaccounted for.
Quote:
Originally Posted by PontiacGTX View Post

You can calculate the TDP with
Another formula could be P(R)= R*(I)^2 plus P(r)=r*(I)^2
Where R is the external resistenace r is the internal reisstance and I is the intensity
The TDP has a slighly loss of the energy used in the circuit and the components on it like resistors,capacitors,voltage leakage
This worth a read

LinkLink

But in video card I have noticed that they talk om the TDP based on the power input from the power connector and pcie slot,meanwhile the intel TDP is a maximum for a relative load maybe higher and could reach the number that intel says.For example my 2600k has a 105w TDP more or less at 1.240 with 4.4ghz(throught Hwinfo64)
Also forgot

OC Wattage = TDP * ( OC MHz / Stock MHz) * ( OC Vcore / Stock Vcore )^2

But why the gpu are kept as cool? The heatsinks are in contact with the die where in a processor has a heatsprrader because the die density is too high and there should be a way to spread the heat for a more effective heat transfer to the heatsink
 

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8pin is not 100W, it's 150W.
 
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