Phases - are lots generally good or only necessary for more demanding scenarios?

[mikeymikec]

Motherboard phases, that is. I read an article on the Internet about them, but I'm not 100% sure of their importance generally speaking - do they increase the chances of a motherboard lasting a very long time?

 

[VirtualLarry]

Well, it's possible to have many smaller phases, or a few more powerful ones.

In theory, more phases allows the load on each phase to be less, meaning that they will run cooler and last longer.

However, my P35-DS3R v1.0 Gigabyte board, is only 4 or 5 phases, and it has lasted quite a long time, always overclocked to the max.

So component choice factors in strongly to durability. (These were among the first Gigabyte boards to be part of their "Durable/Ultra Durable" series. I think the 965P-DS3 was one of the first.)

 

[Cookie Monster]

Basically on a motherboard, there is a DC-DC converter located next to the CPU socket to convert 12V (that comes from the 4/8pin I assu,e) to the required voltage to the CPU. Lets just call this the CPU power stage. People refer this to all sorts of things from PWM circuitry to CPU phases etc ignore these as they make no sense whatsoever.

This "phase" normally refers to duplicating the main power components which are
1) The inductor/choke - square things that are located near those solid state capacitors next to the CPU socket.
2) Mosfets - flat square chips that you see near the square things.

So say a phase is made up of one capacitor/one inductor/2 mosfets. Now if you have 4 phases, youll see the above x4 all neatly located near each other.

They do this so that the "load" may be spread out instead of having to use components that are large and bulky to handle some of that load. Due to cost, heat, size and given electrical requirements, its very difficult to get away with a "single phase" converter which are pretty much the norm.

So you end up with motherboards with the CPU power stage containing 3~4 phases using cheap/average components to satisfy the CPU power requirements. Now obviously some of the high end boards use very good components i.e. get less hot/potentially last longer, but say having 12+ phase may not really be any different to say having 5~6. It would be actually be worse at lower loads in terms of efficency from experience.

The reason I say that is because that CPU power stage with lots of phases and good quality components could probably handle up to 300W of power! But if we look at what the typical CPU consumes in terms of power, alot of that is gone to waste. The designers probably know that they could have gotten away with 5~6 phases which would result in similar efficiency/temperature, but its probably all about the numbers/tick boxes/marketing slides.

Most boards will run for a long time if left in stock. When overclocked, components start to get stressed so typically higher end boards which have better components (which tend to have more "phases") would probably do well here compared to some el cheapo motherboard.

 

[BonzaiDuck]

. . . Most boards will run for a long time if left in stock. When overclocked, components start to get stressed so typically higher end boards which have better components (which tend to have more "phases") would probably do well here compared to some el cheapo motherboard. . . .

. . . Thus, explaining how this is a factor when I choose new mobos. If it will be OC'd, the power-phase design is a criterion; if not, then I spend less. I've had some $85 motherboards which lasted a long, long time. But I wouldn't put them through the stress of custom over-clock tweaks.

 

[bryanl]

The power capacity of a VRM is more important than how many phases it has, and many good motherboards with just 3-phase VRMs could run >90W Pentium 4 or Pentium D CPUs for years.

I prefer to not exceed 75% of a VRM's power rating because the quality of VRMs isn't always good, and if you plan to overclock, look for a VRM made with Japanese capacitors, not just since they're better components but also because they're a sign the manufacturer cared more and used better or higher capacity MOSFETs and inductors as well. Do not assume heatsinks or heatpipes in the VRM will assure reliable overclocking.

 

[nitromullet]

having 12+ phase may not really be any different to say having 5~6. It would be actually be worse at lower loads in terms of efficency from experience.

I was under the impression that on boards with more phases they would be disabled if not needed. The MSI MPower Z77 board even has LED's to show you the number of active phases at any given time.

http://www.guru3d.com/articles_pages/msi_big_bang_z77_mpower_review,4.html

 

[Cookie Monster]

I was under the impression that on boards with more phases they would be disabled if not needed. The MSI MPower Z77 board even has LED's to show you the number of active phases at any given time.

http://www.guru3d.com/articles_pages/msi_big_bang_z77_mpower_review,4.html

Oh yeah your right. This is one ways of having the best of both worlds

But I think this has been something of recent times (started to be used back from 4 years ago maybe with the whole motherboard phase overkill? + cost of motherboards have gone up gradually including the component quality as well).

 

[onething]

Thanks for the explanation Cookie Monster, nice and concise, I like it!