Now, let's try something controversial - power phases. We've all heard about them, so what are they? Phases are just a fancy way of saying parallel power delivery, but how well does that work?
Well, here's an analogy. Let's say you need to carry a heavy rock. Being the macho man you are, you can probably lift it by yourself (and break your back in the process!). Why not get another person or two to help you lift it instead? With three people (three phases) lifting, the actual weight (load) lifted by each will only be a third of the original weight (load).
Of course, this sounds good in theory, but remember, extra phases can also be used to conceal the use of substandard components. Using the same analogy as above, imagine what happens if one of your friends trip over a stone (substandard equipment). You and your remaining friend will suddenly have extra weight (load) to bear, although as far as anyone is concerned, there are still three people (phases) handling the rock (load).
So, be very wary about motherboards touting multiple phases. Multiple phases are always a good thing - the more phases there are, the better. But pay less attention to that marketing pitch and more to reviews that put the motherboard under a heavy load. That's how you separate the wheat from the chaff.
To further confuse you, some motherboard manufacturers are touting parallel phases. As we mentioned above, phases already mean parallel power delivery. So, how can there by a parallel of something that is already parallel? It's perplexing alright. What they really mean by parallel phases is that for each phase, the load is further distributed along two parallel circuits which terminate in a single current source before it reaches the processor.
Think of it this way. Each phase is a river which splits into two smaller rivers because the impedence created by the island dividing them is too great to overcome. They then join back into a single river at the end of the island to flow out to sea (the processor). Why bother doing this? Well, it reduces load on any one set of components, and obviously 8 parallel phases sounds better than just 4 "normal" phases, right?
The only motherboard I know of that currently uses digital PWM is the DFI LANParty UT ICFX3200-T2R motherboard (a real mouthful, isn't it?) which is based on the RD600 chipset. It uses a combination of ceramic capacitors, Cooper Bussmann SMD inductors, high-speed MOSFETs and a Voltera VPR series digital PWM controller, which is generally the system of power management employed on more power-hungry graphics cards. It has finally made the jump to the processor.
I can't say much about this since Voltera's datasheets are under non-disclosure agreements and are not therefore not accessible to the public. However, if power-hungry graphics cards use Voltera's digital PWM controllers, there must be a really good reason. I can't comment much because that would require the datasheets and circuit diagrams which I don't have. However, this whole digital PWM business is something I'm personally looking forward to learning.
For those who are interested, here's a link to the datasheet of the Cooper Bussmann inductors made specifically for the Voltera VPR - http://www.cooperet.com/library/products/PM-4131%20CPL%20Series.pdf.
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