Thread: Amd Athlon Xp 2200

It depends by your motherboard construction - cpu core voltage stabilizer can runs from 12v or from 5 volt. How to determine it ? - very simple way - look at your motherboard, if you see there additional 4pin 12v socket ( like in p4 systems) - 90% means that cpu runs from 12v, if not - runs from 5v rail.

it dont

This page reports that "Athlon and Pentium 4 CPUs run entirely on the +12V rail"

http://www.firingsquad.com/print_art...rticle_id=1162

This page reports that "Athlon and Pentium 4 CPUs run entirely on the +12V rail"

http://www.firingsquad.com/print_art...icle_ id=1162

New motherboards could runs from 12v, but old runs cpu from 5v rail.I have old Shuttle ak32 motherboard which supports athlon XP 2000+ and higher AND IT POWERS CPU FROM 5V RAIL!!! So as i wrote above - powering of cpu depends by motherboard construction.

Bazza_84
Please describe the model of your motherboard, i'll try to find photo and characteristics of mobo. Or you can post hi-res photo of your motherboard.

ok i have an abit kx333 motherboard, high res photo on site

http://www.abit.com.tw/page/uk/mothe...MTYPE=Socket+A

Cheers Guys for all ur help so far

Baz

well, I Have an Asus k78nx motherboard with a xp 2600 AMD and it doesn't have the 4 pin pentium 4 type connection. I don't think I've ever seen that connection on AMD type motherboards. BUT. I do believe my board supplies 12 volts to the processor since I have trouble running it on my 160 wall m2 atx. (I have to have fans running from a nother power source for the pc to boot up correctly.

Snortonnorton

I have trouble running it on my 160 wall m2 atx.

look at m2 atx characteristics - it's only 8A on 5v rail
Thats why it couldn't powers your system.
Bazza_84
Cpu stabilizer on your mobo powers from 5 v rail - there is socket A on mobo - so 99,9% 5v rail.Why? - just calculate a current= CPU power/ voltage ( for 5 v and for 12 v rails ) And think about how 1 wire for 12v on 20 pin molex connector can provide high current .... - it can not(18 or 20 awg)!!! So it powers from 5 v rail. Here is also a way how to choose power supply - calculate current as i described and look at psus characterisics - current on "cpu power" rail must exceed calculated value at minimum 10% , best way 20-30%
here is a different cpu power taking description http://www.techpowerup.com/cpudb/
Snortonnorton you also can do the same calculations.

If you don't trust me you can just measure input voltage on cpu's core voltage stabilizer by using multimeter, then you will know it 100% which rail

Hah - amd 64 powers really from 12v rail - look at mobos which support them - there is a 12v 4 pin socket like in p4 systems.

Ok. look at the pic.

here is 3-phase core voltage stbilizer marked by red lines.
you can see 6 transistros marked by green dots.
Right side transistors- syncronous rectifier - if you look at the tops of transistors, you'll see that each top runs to it's own coil.

We are iteresting left side!!!
- look at blue dots - at mobo left side transistors tops connected together on board - hereis it ! Here we can measure the powering voltage 5 or 12 rail, but this is not the best way - also at the top left conner you can see a coil - measure the voltage before it.
Thats how you can determine which rail powers your cpu.
When you measuring voltage your computer must work and you must understand what you do- if you don't- don't do This!

On another mobos principle the same - you need to find transistors tops of which connected together( more than enough) - and the coil which connects to them- this will be the reference point

More safely for mobo method(i think it's a best method- computer is in off state and your dont need anything -only mobo) is measure resistance between reference poin which i described and 5v and 12 v pins of 20-pin molex socket on mobo. Where it will be near 0,5-1 ohms - that rail powers cpu. Remeber - your mobo must be disconnected form psu before you begin to mesure resistance, and all devices must be disconneted from mobo. This method for peoples who don't want to risk hot working system

man!!!!!!!

so i need a psu that supplies 13A on the 5v rail?

62w / 5 = 12.4 round up to 13

so i would need the opus 250