Intel P965 is heavy on the juice

CHIPSETS SEEM to be taking more and more juice these days, and you can't ignore them when you're trying to keep your system cool. nVidia's latest nForce5 series have come under stick from some hardware sites for being power-hungry, however AMD like to make the point that their CPUs power contains the north bridge too.

So how significant is this? We decided to investigate how toasty the P965 chipset would get compared to the previous generations: 945P and 975X.

Bear in mind the three chips have very similar features, with I/O such as SerialATA being handled by the south bridge: all support a 1066MHz FSB, dual-channel RAM and 16x PCI express, although the 955X can split this into two 8x channels for dual graphics cards.

The main thing offered by P965, other than official Cointreau support, is the ability to run the DDR2 at 800MHz instead of 667 on the 945 and 975. How much power does this add?

Wonder no more: here are the numbers:

North Bridge	975X	945P	P965
South Bridge	ICH7	ICH7	ICH8
Bus Speed	1066MHz	1066MHz	1066MHz
Memory	667 x 2	667 x 2	ICH8
NB TDP	13.5W	15.2W	19W
SB TDP	3.3W	3.3W	4.1W
Total TDP	16.8W	18.5W	23.1W

The new north bridge takes up to 19W, a 5.5W rise over 975X and almost the same as a Dothan Pentium M! The idle power is also 10W, so Intel still have some work to do in order to turn Broadwater into a mobile product.

We'll be very interested to see how much extra juice is needed when the Vista-ready graphics is turned on. The 945G sticks on another 7W over the graphics-less version; not exactly X1900 levels, but still pretty beefy. G965 could be higher still, but we'll let you know when we hear. In the mean time, heatsink designers will be kept busy! µ