Zuhl3156

kwkrnu72
So, 6+1 or 14+3 isn't going to deliver MORE volts, just more steady voltage for more stable overclocking.....  I wonder, though, if the better power phase will handle higher voltage better in terms of thermals?

This is the best explanation I found where it is compared to a car engine: http://www.techspot.com/community/topics/what-are-power-phases.169661/
This is something I have been wondering about recently too since it was never explained to me but is getting more and more attention.

Tweaked

un4givn85
So what does the +1 mean? Why not just call it 5 instead of 4+1?

Because that portion of the power is shunted to the memory controller as explained in this excerpt from the above link.

The +2 part of the equation (8+2, 12+2 etc.) refers to the same principle, but in this instance the current is going to the memory controller (either chipset, or in the CPU if the controller is part of the CPU package).

 
So, 8 or 12 phases go one direction, and 2 phases go another.  It delineates how many phases of power go to which components on the motherboard.  

ty_ger07
I highlighted a number of things for you.  I hope this helps:

First of all, I would like to clear up something which has been made a little bit misleading.  The increased number of power phases do not necessarily smooth out the voltage output.  The image posted by tweaked is very misleading because that is not what the voltage ouput looks like. ... Not even close!  If you look at his first picture with a single phase and compare it to his second picture with three phases, you may think that of coarse it looks smoother with three phases.  This is not necessarily the case!  The output is filtered by the inductors and capacitors.  It is a DC to DC buck converter system and the output voltage is not anywhere even close to a sine wave at the end.  There actually is no sine wave in this whole system to begin with -- because it is a square wave and the square wave only exists from the voltage regulator up to and through the MOSFETs.  After the square wave output of the MOSFETs, the inductors and capacitors filter the square wave and their output should be nearly ripple-free and look like normal DC and will not ever look anything even close to the AC represented in tweaked's illustrations.
 
More phases may equate to smoother power delivery.  Also, more phases may equate to higher current capability.  But buyer beware!!  Just like cheap computer manufacturerers sometime sell an excessive quantity of cheap low performance memory in their product because some buyers don't know any better and think that more memory means a faster computer, some video card and motherboard manufacturers are exploiting similar tactics regarding power phases.
 
Fewer power phases coupled with well engineered filtering in the inductor/capacitor section can be much better than a bunch of power phases tossed on a product with poor engineering.  Additionally, the voltage regulator controller chip is very important both in maintaining desired voltage output and in determining whether or not the user can easily interract with their product in terms of changing voltages.  The voltage controller chip may not be adjustable by the user at all, may be adjustable only through proprietary methods with strict limits, or may be adjustable openly using industry standard SMBus or I-squared-C, and may even allow for adjustment of the output PWM frequency.  Cheap products with lots of phases are just cheap products with lots of phases.  All the individual components illustrated in the picture above need to be chosen carefully in order to match together in a great product.
 
Lastly, one should remember that if one does not need additional power phases, one should consider avoiding additional power phases if performance per watt and heat output are crucial factors in their system component choices.  But, if you really want to maximize your potential and aren't worried about the reduced efficiency and increased cost, it is hard to beat a product with a bunch of very well engineered power phases coupled with a voltage controller chip which is easily accessible and tunable.
 

kgrames

willem445
I know this is an old thread but I wanted to clarify some things in case anyone else stumbles across this thread as I did. I saw a thread about the Zotac GTX 1080 showing a large number of power phases on the PCB, which got me wondering, what exactly are these phases. Being an EE student, power electronics interest me so I looked into it. 
 
The pictures Tweaked referenced are extremely misleading. The second picture just illustrates 3 phase power, what the US power transmission system consists of, 3 120VAC phases and a common. The first image is just one of those 3 phases, which is what you would see at an electrical outlet. The PSU converts the 120VAC to 12VDC so the GPU never sees anything close to AC power. The phases of the GPU power system are just multiple DC-DC buck converters. The purpose of the buck converters is to reduce the 12VDC down to whatever the GPU die requires, around 1V. Now the design of DC-DC converters is difficult for voltages around 1 volt. You have to deal with efficiency, duty cycle, switching frequency, etc which all work against each other.
 
Anyways, for such small voltages, the die requires massive currents. If the voltage conversion was done in just one stage, you would need much larger inductors and smoothing capacitors to handle the large current and voltage ripple requirements of the GPU. Efficiency also suffers here. When more phases are added to the buck converter system, the load on the FETs and inductor is greatly decreased. This reduces the inductor size required, reduces power losses across the inductors and FETs increasing power efficiency, this also helps immensely in spreading the heat evenly, reducing thermal hotspots. Current ripple is also improved also lowering voltage ripple. So with more phases, such as on classified cards, the converters can handle the increased current requirements seen with overclocking and help spread the increased heat more evenly while also reducing ripple at the input to the GPU die. 
 
Ty_ger07's explanation is very good but lacked some of the more technical details. He is also correct in that the quality of components is also very important. Special components help to further reduce losses and increase efficiency while also lasting longer. I wouldn't doubt that EVGA uses high quality components as their cards have always performed very well. 
 
I hope my explanation makes sense and helps out people who are curious about phases as well. Feel free to correct me if I have made any mistakes. It would be very interesting to actually see a schematic of one of these cards to see how they accomplish power delivery. 
 
Also found this based on an IC found on a high resolution photo of an ASUS GTX 980. The data sheet shows the common configuration for 8 phase power control if anyone is interested. 
 

Great explanation!