Question Understanding CPU TDP and "T" versions of intel processors.

elsmandino

Junior Member
Jul 19, 2009
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Hi there.

I have been reading doing some research on TDP levels on CPUs and I am really struggling to understand what this means.

For instance, take the i3-4330 and the i3-4330T. The first has a 53W TDP rating, whereas the latter has a 54W TDP rating.

1. If completely idle, do these CPUs have the same power draw?

2. If both CPUS are run at 100%, the "T" version is going to run at a slower rate but then will take longer to complete the task. This being the case, are the two CPUs going to use the same net amount of energy to complete said task?
 

coercitiv

Diamond Member
Jan 24, 2014
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For instance, take the i3-4330 and the i3-4330T. The first has a 53W TDP rating, whereas the latter has a 54W TDP rating.
  1. If completely idle, do these CPUs have the same power draw?
  2. If both CPUS are run at 100%, the "T" version is going to run at a slower rate but then will take longer to complete the task.
  3. are the two CPUs going to use the same net amount of energy to complete said task?
i3-4330 has a 54W TDP and a base frequency of 3.5Ghz
i3-4330T has a 35W TDP and a base frequency of 3Ghz

Answers to your questions, which I reordered a bit for clarity:
1. Yes, at idle they use the same amount of power.
2. Yes, the T version will run slower at 100% and will take longer to complete the task.
3. The two CPUs will use different amounts of energy to complete a task. The T variant will generally use less energy, but this may change on a case by case basis (workload length and type may change the outcome).
 
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mikeymikec

Lifer
May 19, 2011
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The sole point of the T-class Intel processors is that they're clocked at a lower rate to significantly limit their energy usage so they can be used in a chassis with limited cooling potential (e.g. an all-in-one PC or some other super-slim PC build).

It's not a statement of energy efficiency unless one's only metric for efficiency is 'use less energy', at which point one should start comparing that i3 to phone-class processors, the Atoms and other completely different types of processor. For example, I'd like it very much to have a processor that uses a tenth of the energy that my i5-4690k uses, but not if that meant that the OS takes five minutes to start and Firefox takes 20 seconds to load another page.
 

elsmandino

Junior Member
Jul 19, 2009
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Thanks for your responses.

So am I right i thinking that a "T" version of a CPU makes little sense in a full desktop PC as you are artificially limiting its potential for no gain at all?
 

elsmandino

Junior Member
Jul 19, 2009
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The sole point of the T-class Intel processors is that they're clocked at a lower rate to significantly limit their energy usage so they can be used in a chassis with limited cooling potential (e.g. an all-in-one PC or some other super-slim PC build).

It's not a statement of energy efficiency unless one's only metric for efficiency is 'use less energy', at which point one should start comparing that i3 to phone-class processors, the Atoms and other completely different types of processor. For example, I'd like it very much to have a processor that uses a tenth of the energy that my i5-4690k uses, but not if that meant that the OS takes five minutes to start and Firefox takes 20 seconds to load another page.
I think I am starting to see the point of the "T" CPUs now.

So you could stick either an i3-4330 or an i3-4330T in a tiny enclosure and they would be identical at idle.

It is only at high loads that there becomes an issue as the i3-4330 would go beyond the tiny enclosure's ability to remove the heat, meaning that the other components would get hot and the fan would become irritatingly noisy.

The i3-4330T is deliberately limited to prevent the CPU, from reaching such a temperature and thus the components remain less stressed and things remain quieter/cooler (at the costs of taking longer to carry out the process).

Is that an accurate summary?

I was going to say that if the 4330 has a max clock of 3,5Ghz and the 4330T has only a max of 3.0Ghz, why (if you are looking at the later CPU), just go with the G3220 (which also has a maximum of 3.0Ghz). However, I realised that you would of course be sacrificing cores in doing so.
 

Insert_Nickname

Diamond Member
May 6, 2012
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It is only at high loads that there becomes an issue as the i3-4330 would go beyond the tiny enclosure's ability to remove the heat, meaning that the other components would get hot and the fan would become irritatingly noisy.

The i3-4330T is deliberately limited to prevent the CPU, from reaching such a temperature and thus the components remain less stressed and things remain quieter/cooler (at the costs of taking longer to carry out the process).

Is that an accurate summary?
Yes, that about sums it up.

The non-T and T actually have the same temperature tolerances. It's just a question of how much heat your cooling system has to remove. With a large enough heatsink, you can even passively cool a 35W CPU. At least some case airflow is required though.
 

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