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10 + 2 phase power delivery - WHAT IS THIS?
- Thread starter Viper69
- Start date
- Joined
- Mar 27, 2011
- Location
- Soviet Mexico
10 phases for cpu i am guessing and 2 for ram.
The more phases the smoother the power delivery is and less ripple their is during load.
The more phases the smoother the power delivery is and less ripple their is during load.
- Joined
- May 10, 2009
For most users it is pure marketing and really makes very little difference.
For extreme users it is (kind of) a measurement of how good the CPU voltage regulators are.
More phases means smoother power and more power available, should the CPU want it.
Mostly it's marketing though.
Generally on the X+Y phase things it means that the CPU cores get X phases, with Y phases for the other bits integrated into the CPU (graphics, memory controller, PCIe controller, that sort of thing).
For extreme users it is (kind of) a measurement of how good the CPU voltage regulators are.
More phases means smoother power and more power available, should the CPU want it.
Mostly it's marketing though.
Generally on the X+Y phase things it means that the CPU cores get X phases, with Y phases for the other bits integrated into the CPU (graphics, memory controller, PCIe controller, that sort of thing).
- Joined
- Jun 8, 2005
Short electronic preface:
Assume we are talking about buck converters. The way they work is you have an inductor and a MOSFET. The MOSFET gets toggled on and off really fast, and this action "charges" the inductor. The output voltage equals to the ratio of MOFSET ON / (mosfet on + mosftet off). For example, keeping mosfet on 50% of the time results in voltage being half of input voltage.
You have the big ATX power supply that takes in the 120/220V AC from the wall. It then converts it down to 3.3/5/12V DC to give to the motherboard. However, your CPU requires 0.7~1.4V, and the RAM requires 1.3~1.6V. In addition there are other parts on the motherboard that need their own voltage.
Therefore the motherboard has it's own switching power supplies. Now, the processor requires a LOT of power [100-200watts], at a very low voltage ~1v. As we know power = volt*amp, so the CPU power supply need to be able to deliver 200 amps @ 1volt. The power supply losses depend on amperage not voltage(loss = resistance*current^2), and goes up squared. That makes a huge problem for changing over from 12 volt down to 1 volt.
What we have to do to satisfy the 200 amp requirement is to have multiple power supplies and parallel them together. Specifically you want to have separate MOSFETs/inductors [biggest losses]. If we make 10 power supplies and connect everything perfect then every supply only has to give 20 amps, which results in 10 times less losses. [200^2 vs 10*20^2].
This structure is called multiphase buck. Each "mosfet + inductor" is called a phase. There is a central controller that controls every single MOSFET and switches them on and off to get good control of voltage and to make sure current is spread evenly across all phases.
The more phases the easier it is to build bigger current power supplies. Therefore if we use the same MOSFETs/controller/inductors then a 12 phase power supply is superior to 10 phase power supply which is then superior to 8 phase power supply. There is also a bit that you can get better voltage regulation and faster voltage swings with more phases.
Generally the motherboard manufacturers mean CPU phases + memory phases. So, in your example 10+2 means 10 cpu phases [remember the 200w?] and 2 means 2 memory phases. The more the merrier, but the type matters as well. Good capacitors with good quality inductors will make a power supply more efficient which is good news
.
Assume we are talking about buck converters. The way they work is you have an inductor and a MOSFET. The MOSFET gets toggled on and off really fast, and this action "charges" the inductor. The output voltage equals to the ratio of MOFSET ON / (mosfet on + mosftet off). For example, keeping mosfet on 50% of the time results in voltage being half of input voltage.
You have the big ATX power supply that takes in the 120/220V AC from the wall. It then converts it down to 3.3/5/12V DC to give to the motherboard. However, your CPU requires 0.7~1.4V, and the RAM requires 1.3~1.6V. In addition there are other parts on the motherboard that need their own voltage.
Therefore the motherboard has it's own switching power supplies. Now, the processor requires a LOT of power [100-200watts], at a very low voltage ~1v. As we know power = volt*amp, so the CPU power supply need to be able to deliver 200 amps @ 1volt. The power supply losses depend on amperage not voltage(loss = resistance*current^2), and goes up squared. That makes a huge problem for changing over from 12 volt down to 1 volt.
What we have to do to satisfy the 200 amp requirement is to have multiple power supplies and parallel them together. Specifically you want to have separate MOSFETs/inductors [biggest losses]. If we make 10 power supplies and connect everything perfect then every supply only has to give 20 amps, which results in 10 times less losses. [200^2 vs 10*20^2].
This structure is called multiphase buck. Each "mosfet + inductor" is called a phase. There is a central controller that controls every single MOSFET and switches them on and off to get good control of voltage and to make sure current is spread evenly across all phases.
The more phases the easier it is to build bigger current power supplies. Therefore if we use the same MOSFETs/controller/inductors then a 12 phase power supply is superior to 10 phase power supply which is then superior to 8 phase power supply. There is also a bit that you can get better voltage regulation and faster voltage swings with more phases.
Generally the motherboard manufacturers mean CPU phases + memory phases. So, in your example 10+2 means 10 cpu phases [remember the 200w?] and 2 means 2 memory phases. The more the merrier, but the type matters as well. Good capacitors with good quality inductors will make a power supply more efficient which is good news
.
Last edited:
- Thread Starter
- #6
Short electronic preface:
Assume we are talking about buck converters. The way they work is you have an inductor and a MOSFET. The MOSFET gets toggled on and off really fast, and this action "charges" the MOSFET. The output voltage equals to the ratio of MOFSET ON / (mosfet on + mosftet off). For example, keeping mosfet on 50% of the time results in voltage being half of input voltage.
You have the power supply that takes in the 120/220V AC from the wall. It then converts it down to 3.3/5/12V DC to give to the motherboard. However, your CPU requires 0.7~1.4V, and the RAM requires 1.3~1.6V. In addition there are other parts on the motherboard that need their own voltage.
Therefore the motherboard has it's own switching power supplies. Now, the processor requires a LOT of power [100-200watts], at a very low voltage ~1v. As we know power = volt*amp, so the CPU power supply need to be able to deliver 200 amps @ 1volt. The power supply losses depend on amperage not voltage(loss = resistance*current^2), and goes up squared. That makes a huge problem for changing over from 12 volt down to 1 volt.
What we have to do to satisfy the 200 amp requirement is to have multiple power supplies and parallel them together. Specifically you want to have separate MOSFETs/inductors [biggest losses]. If we make 10 power supplies and connect everything perfect then every supply only has to give 20 amps, which results in 10 times less losses. [200^2 vs 10*20^2].
This structure is called multiphase buck. Each "mosfet + inductor" is called a phase. There is a central controller that controls every single MOSFET and switches them on and off to get good control of voltage and to make sure current is spread evenly across all phases.
The more phases the easier it is to build bigger current power supplies. Therefore if we use the same MOSFETs/controller/inductors then a 12 phase power supply is superior to 10 phase power supply which is then superior to 8 phase power supply. There is also a bit that you can get better voltage regulation and faster voltage swings with more phases.
Generally the motherboard manufacturers mean CPU phases + memory phases. So, in your example 10+2 means 10 cpu phases [remember the 200w?] and 2 means 2 memory phases. The more the merrier, but the type matters as well. Good capacitors with good quality inductors will make a power supply more efficient which is good news
Thanks!
- Joined
- Mar 12, 2002
Shadow that is pretty much the best simple explanation to power phases Ive read.
The current standard on high end AMD stuff is 8+2 phases with mid/low range boards sporting 4+1 and low end 3+1.
Of course its up to mobo manufactures to decide what they want and there are a couple(atleast one) 12+2 phase AM3+ boards.
Im not sure what high end Intel stuff is sporting but 10 phases sounds pretty nice to me.
The current standard on high end AMD stuff is 8+2 phases with mid/low range boards sporting 4+1 and low end 3+1.
Of course its up to mobo manufactures to decide what they want and there are a couple(atleast one) 12+2 phase AM3+ boards.
Im not sure what high end Intel stuff is sporting but 10 phases sounds pretty nice to me.
- Joined
- Jun 8, 2005
Thank you! I tried. If you want I can answer more questions or give a more technical explanation as well
- Joined
- Dec 31, 2004
- Location
- Osan AB, South Korea
How do you know if a board is using high quality caps and inductors?Good capacitors with good quality inductors will make a power supply more efficient which is good news
Great writeup! I've been wondering the same thing myself for a while!
- Joined
- Jun 8, 2005
For that you have to obtain the manufacturer + number and find a datasheet. The datasheet will have all kinds of pretty numbers in there like
*ESR [resistance, generally want as little in caps/inductors]
*MTBF[mean time between failures]
*Variation [how much will the numbers deviate from stated value]
Additionally MOSFETs will have gate charge [want as little as possible to switch quickly, switching times, resistance [less = less heat = very good].
Now, the way to get the manufacturer + number is generally very easy for MOSFETs [only a couple big makers for low-ohm MOSFETs afair]. However, it is more difficult for capacitors and even more so for inductors.
All those characteristics have to be carefully balanced against the cost. Is it worth to use 10 mOhm as opposed to 5 mOhm MOSFETs or can we just use 2 MOSFETs in parallel doubling the gate charge? Or can we just afford double the heating, which would lower part lives?
Lastly, the controller is critically important. You have to know exactly when to switch MOSFETs on and off and which ones. Too late and the voltage swings. Too soon and the voltage swings again. Too low of damping? Now you have an oscillation of voltage, which your processor will certainly not like. And there are tons of those controllers, and many of them are customly made.
Therefore comparing different switching power supply techniques is hard [inductors + contrllers are so different]. However, with capacitors it's easier to distinguish cheap chinese copies from expensive low-esr ones.
- Joined
- Mar 12, 2002
Thank you! I tried. If you want I can answer more questions or give a more technical explanation as well
No its good, I already know what the phases do and how they work. However, the explanation you gave is both simple and clear. Something most explanations of how power phases work generally lack.
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