small Pentium 4 buying guide
I think everybody now knows about the Prescott. Intel developed the first multi-functional CPU. It cannot only do all the work in you PC, you can also use it for much more: http://home.arcor.de/jojo4u/silentstuff ... escott.swf
So the Prescott is hot. But you want to buy it nevertheless. Maybe because you thrust Intel more or you need the extra power in multimedia applications.
So let's list, what Prescotts are available for the designated future socket 775:
type Ghz Cache TDP C1E EIST NX 64bit
TDP - Thermal Design Point
520 2.8 1024 84
530 3.0 1024 84
540 3.2 1024 84
550 3.4 1024 115
560 3.6 1024 115
520J 2.8 1024 84 x x
530J 3.0 1024 84 x x
540J 3.2 1024 84 x x
550J 3.4 1024 84 x x
560J 3.6 1024 115 x x
570J 3.8 1024 115 x x
630 3.0 2048 84 x x x x
640 3.2 2048 84 x x x x
650 3.4 2048 84 x x x x
660 3.6 2048 115 x x x x
The TDP is Intels guideline for the sizing of the cooling solution, it does not represent the maximum power reachable:
Chris Hare wrote:
The Estimated Max Power Dissipation numbers are based on the fact that Intel estimates the power dissipation for various software applications and sets the Thermal Design Point as the upper limit for how far these applications might push the Pentium 4. Intel states: "Processor power dissipation simulations indicate a maximum application power in the range of 75% of the maximum power for a given frequency." So the Est Max Power Diss was calculated by dividing the TDP by 75%.
Nevertheless you want obviously a TDP of 84W since the higher clocked cores are needing more power.
C1E - Enhanced Halt State
This means that your CPU clocks itself down to 2.8Ghz and lowers the voltage from 1.4V to 1.2V automatically when there's nothing to do. You need BIOS support for this and Windows XP SP2.
So what are the advantages? Have a look at the following picture:
http://www.hardwareluxx.de/jens/Benchma ... =51&cid=80
On top you can see the new Extreme Edition 3.75Ghz which has no C1E enabled. Following are the 560-540 types without C1E as well. Then you can see the C1E-enabled 570J with around 27W less AC power of the whole system.
EIST - Enhanced Intel SpeedStep
This is a bit like Cool'n'Quiet but not as powerful. It works together with C1E, so there is no change in idle power usage.
But when the CPU is between idle and full power, there are now intermediate frequency/voltage steps from 2.8Ghz upward existing.
What does it bring? Please have a look at the last picture:
http://www.computerbase.de/artikel/hard ... gsaufnahme
The first set is idle - EIST has no advantage
The second set is HD WMV playback - EIST cuts the power by over 20W AC
The third set ist burning the CPU - EIST has no advantage.
Unfortunately, EIST doesn't seem to switch to highest power whenever it could be:
1. tomshardware.com reports that encoding a MP3 with lame needs 10% more time with EIST enabled (but leaves them uncommented
2. hardtecs4u.de reports that compressing with WinAce needs 5% more time and games loose around 1 frames/sec
3. computerbase.de reports that during rendering the CPU sometimes refused to clock up
In this light, EIST seems to be a bit too much biased towards power-saving. I will add new reports about that.
From a low-power standpoint it is best to buy a 520J-550J or a 630-650 model. EIST is a little bit difficult to judge nowadays, but giving the problems with the benchmarks, I would disable it until it becomes fixed.