Do ULV Core i5 CPUs consume the same power as i7 CPUs if they use the same TDP?

Question

If you have a Core i5 CPU and its TDP is 17W and there is a Core i7 CPU which also has TDP 17W, will they consume the same battery power even though one runs faster?

I am referring to:

• Core i5-3427U
• Core i7-3667U

Answer 1

TDP or Thermal Design Power is the maximum amount of power dissipated by a component or system. That a CPU has 17W TDP means that it will not under any normal operating circumstances dissipate more than 17W of power as heat.

Since (somewhat simplified) all power used by electrical components eventually becomes heat and no electrical component can create heat without using some amount of power (meaning heat dissipation and power consumption can be considered as equivalent for our purposes), two components with the same rated TDP will have the same maximum input power requirement. However, the normal or average power, especially in a given situation, may be lower for one of them.

For example, you may be able to step down the frequency of the faster CPU more than you can step down the frequency of the slower CPU while retaining the user experience you want. In that case, the faster CPU may actually consume less power for the same user experience.

Answer 2

Adding to Michael Kjörling excellent answer you will find that they use about the same amount of power overall. Here is a comparison for various Ivy Bridge processors (check the Power Consumption section). FYI, the i7 should be "in the order of" 15% more powerful then the i5.