# Modding Estimating Total Sytem TDP

Discussion in 'Modding' started by Zeroignite, 25 Jan 2009.

1. ### ZeroigniteSo I decided to simulate a Universe

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I have a question relating to my future Tcherenkov Blue OilPC build (see sig).

I've been playing with the thermal parameters a bit, trying to get an idea of how feasible full passive cooling is and to plan the radiator dimensions. I know the math well enough now. However, I have a bit of a problem: I don't know how to estimate the amount of heat generated by the entire rig.

The TDP is widely available for CPUs, and for the PSU it's easy enough to calculate from the stated efficiency [TDP=output power x (1-efficiency)]. However, I don't know where to find thermal data on other components- GPU, mobo, drives, etc.

Does anyone know where I could find suck information, or any of other methods of figuring out how much heat the entire system is producing? Google is not very helpful.

I created a separate thread so that other can find it more easily.

2. ### MoriquendiBit Tech Biker

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Get a watt meter. By and large all the power that your computer sucks from the wall ends up as heat inside the case, there will be a little that gets turned into noise but the vast majority will be heat since it doesn't do any work in the physics sense.

Moriquendi

3. ### ZeroigniteSo I decided to simulate a Universe

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So the TDP would be PSU inefficiency PLUS output?
That's a ton of energy to dump...

4. ### Ending CreditsBunned

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It's a couple of hundred Watts usually.

5. ### MoriquendiBit Tech Biker

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Yup, if you're oil-cooling the psu the TDP is what the meter reads at the wall, everything that comes out of the wall eventually ends up as heat in the case ( this is a simplification but the other ways that power is dissipated are negligible in comparison) .

If you're not oil-cooling the psu then the TDP of the system is the wall reading multiplied by the efficiency of the PSU, for example:

You have an 80% efficient PSU and the watt meter reads 100w. 80w gets fed to the system and 20w gets wasted in the PSU as heat.

Very few systems every use the rated power output of the PSU, people buy 7-800 watt PSUs because they think they need it when actually the computer uses less than 200w. By using a watt meter to measure the actual power consumption you wont be over-engineering the cooling system.

Moriquendi

6. ### ZeroigniteSo I decided to simulate a Universe

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Or, because my multimeter can't measure more than half an amp, I could use a power draw calculator like this?

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That's one of the few power calculators out there with a good reputation. I used it as a reference point and eventually downgraded from a 750 watt PSU to a 620 watt. Although Corsair's power draw calculator seemed pretty fair too... suggesting a 500 or 620 watt PSU (rather than 750 which some of the other calculators suggested).

8. ### MoriquendiBit Tech Biker

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You can buy them at just about any electronics type shop for a tenner, probably less if you hunt around and they're very useful things to have. For example I found out using mine that my PSU draws 14w even when the computer is off which is a significant amount when you consider that the computer is off for much more time than it's on, now I switch it off at the wall.

This is the sort of thing I'm talking about though of course this is a British one.

I wouldnt trust a power calculator.

Moriquendi

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9. ### Nexxo* Prefab Sprout – The King of Rock 'n' Roll

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CPU TDP data can be found here.

Older graphic card TDP data can be found here. For most new drives, manufacturers and review articles have now started to mention TDP as a matter of course. Google is your friend.

Hard drive TDP/energy consumption data can be found here.

CD-ROM drive power consumption is again usually mentioned in the specs. Usually about 10 Watts.

Motherboards typically use about 30 Watts, depending on chipset, although again some reviews now look at this more specifically.

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