Stop calling the VRD the PWM !!! Please?

BillParrish

Supreme [H]ardness
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Aug 25, 2006
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This is wrong terminology and makes you sound like you dont know jack even if the info is mostly ok. Please stop, I know you guys are smart.

" ..."PWM" is a circuit on mainboards to convert the voltage level from power supply unit to provide specific voltage to components (ex. Provide CPU with core voltage). We know that CPU could be the hottest component inside a PC system, and we always care about the heat dissipation of it. Actually, the PWM circuit is quite hot too; especially when CPU is at full loading, large current passes through the PWM circuit and was converted to necessary CPU core voltage. Some ABIT boards show "PWM temperature" on BIOS setup page and Windows hardware monitoring tool. This provides users possible hottest temperature inside the PC chassis, and check whether the air conditioning inside the chassis needs to be enhanced or not. When CPU works heavily, the CPU temperature could be around 60 degree C; nevertheless, the PWM temperature may achieve 70 degree C or even higher; depends on the design of thermal convection. The safety limit of the PWM temperature is about 120 degree C, however, we strongly recommend improving the air flow and heat dissipation inside the PC chassis once it rises to 100 degree C... "

EDIT - PWM is the abbreviation for Pulse Width Modulation.

Close but no bananna the PWM circuity/chip is part of the VRD (Voltage Regulator Down, see note 1 ) circuit that provides the switching signal to the power FETs. This switching signal varies in the length of time it is on, thats the pulse width, and thus controls the amount of voltage the rest of the VRD provides to the load. The PWM controls the power, it does not provide/deliver it.

The "fully digital pwm" is more marketing BS and is probally some kind of misguided reference to the elimination of electrolytics and the new surface mount coupled inductor chip. This big chip has caused a lot of mis-information, all it does is to replace the toroid inductors on older boards and the potted ones, the larger black cubes you see around the cpu area, on newer boards. Perhaps they are using a pwm controller chip that requires less discreet components but a digital PWM controller chip is nothing new. Anyway putting PWM Temp in the bios just shows the software guys dont know hardware. I do not know exactly what temp that is measuring but I doubt its the PWM controller chip and is probally just an thermistor lurking somewhere nearby on the board, it could be built into the PWM controller chip but I would want to know the FET temps, they are what are under stress.

Now, about that big honking new chip back there that does get pretty warm.

It is just inductors, it gets hot because all the power goes through it, its NOT a control circuit of any kind. Its dumb inductors sharing a common core intergrated into a surface mount package. No more inductor whine and probally cheaper and easier to install.

http://www.alcom.nl/images/nieuws/Pu...un i%2006.pdf
Note 3.

For correct identification of parts and proper terminology (so you dont sound like a noob to an electronics person as the guy on XS does to me take a look at the picture below from earlier in the thread where the HS for the FETs has been removed. It shows the major components of the VRD/VRM circuitry very well. (Thanks for excellent pic revenant )

http://i36.photobucket.com/albums/e4...t/IN9-17-s.jpg

Towards the back of the board,bottom of pic, see the IC with a lot of leads ? , That is the pwm controller chip, the brains. It provides the switching signal that tells the small black squares a little to the North, which are power FETs probally, how long to stay on and provide power, they are the workhorses and thats why they are normally under the heatsink. And finally to the far north we have the big honking new inductior package that is part of the filtering system to smooth out the power and help filter out noise and ripple. Thats the three main parts of what is properly called the VRD or VRM (cpu power supply if you like) the PWM control chip, FET power chips, and the filtering circuit for the output. (what is really interesting is notice the lack of capacitors, the normal can type kind anyway, it appears they have replaced the normal low esr filtering electrolytics with surface mount ones and gotten around the need for large values of capacitance by putting several in parallel, least thats what I am guessing from what I can see, the cluster of small smds just north of our new inductor chip. Interesting, could be good, could be not good. )

Note 1: VRD is new Intel designation for all components of the voltage regulator circuit that are "down" on the motherboard. The old term was VRM, voltage regulator module, which plugged into the motherboard. Both refer to the voltage regulator powering the cpu (for this discussion anyway) and are both used even if VRM is not exactly accurate and a bit dated. So VRM or VRD cpu voltage regulator circuit, good, calling it a pwm circuit is not correct when talking about delivering power, pwm is a control circuit. If you made it this far, you get a gold star. All of this has been somewhat simplifed but you dont need the details.

Note 2 : I am guessing a bit that the chip to the south is the pwm controller, based on its location and number of leads, I cant quite make out the chip markings to be sure, but its a pretty good guess, I think.

Note 3: If there is good airflow around the new inductior chip there is probally no real need to cool it but it could not hurt.


This is what happens when you drink too much coffee.
 
Anybody, everybody, this is what set me off, see last couple of pages.
http://www.hardforum.com/showthread.php?t=1148814

I am not looking to offend or flame anyone, its a technical subject and not simple, but with an electronics background it both confuses me and makes the poster of what could be good information less likely to be taken as knowlegable. <--- if I could spell I probally would be taken as more knowledgable, knowledgeable, whatever, made a C in English, A in engineering.
 
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