AMD Athlon II X3 435 vs. AMD Athlon II X3 405e

[KMS]

I am wondering between AMD Athlon II X3 435 and AMD Athlon II X3 405e for HTPC use. Thus, 1) what is the real difference in efficiency between these two, and 2) what is the real difference in power intake?

According to the specs, 435 is TDP 95 W and 405e TDP 45 W, but I assume that the difference is not that big in real life.

[loimlo]

Though I don't have any experience concerning 405e, I guess the difference between 435 and 405e would be negligible like 2~3W given the same voltage/frequency setting. That's what I got between 4800 and 4850e before.

[Vicotnik]

X3 405e is 2.3GHz at 1.1v (that's the default voltage for my 605e anyway). X3 435 is 2.9GHz at 1.425v I think. The voltage seems to be set individually or at least AMD will not give any official numbers. But if we assume those numbers we can do some math using the famous formula that describes the basic relationship between power consumption, frequency and voltage.

P(435) = P(405e) x (F(435) / F(405e)) x (U(435)^2 / U(405e)^2)

Where P is power, F is frequency and U is voltage.

Let's assume a power of 100 for the 405e just to pick a nice number and calculate the power of the X3 435.

P(435) = 100 x (2.9 / 2.3) x (1.425^2 / 1.1^2) = ~211.6

So at stock speeds the X3 435 should consume over double the power of the X3 405e.

[Esben]

Often you can do as good as, or even better than the stock settings of the energy efficient CPUs. So if you're using the 2.9 GHz X3, and reduce clock speed to 2.3 GHz, it's very likely that the voltage can also be reduced to 1.1v or below.