Would someone explain power vrm phases?

[Rehmanpa]

As the title says I'm hoping someone can help clarify what exactly motherboard power vrm phases are. Looking at some x399 motherboards and the Asrock x399 fatality has an 11 power phase vrm and the asus only has an 8 I think. What exactly does this mean? Does it impact cooling performance or cpu overclocking?

 

[Vya Domus]

VRMs supply voltage to the CPU.

More phases = cleaner/stable voltage output and better heat dissipation for the VRMs hence safer operation. It also means the CPU can draw more power when overclocked.

However it is not that simple , the quality of the VRMs themselves matters a lot too.

In other words you can never really tell which board is better looking just at the specs , some review sites also check out the VRM quality in detail so search for that if you want to find out exactly.

 

[Bill_Bright]

and better heat dissipation

That's not a given. As you correctly noted, quality matters, as does case cooling. Generally, it is all about cleaner/stable power - especially with higher clock rates. Heat dissipation, while critical, depends on other factors besides the number of phases.

 

[jboydgolfer]

thats one of the reasons i tend to go with Asrock, up to the 1150 boards they have always had great OC capability, and Stability, but my experience ends at 1150 since i havent personally owned a 1151 Rig, ive built them, just not kept them. Certainly not saying Asrock is best or anything like that, but the boards i have owned/bought have always had better when compared to the other option in my budget/build range. If you find one with More power phases, it could be a sign of a better board.

 

[Vya Domus]

That's not a given.

I was referring to a scenario where you have the same mosfets with the same quality but more phases in the VRM assembly. Given the same current/voltage each mosfet should dissipate less heat individually hence achieving safer operation.

 

[Bill_Bright]

If you find one with More power phases, it could be a sign of a better board.

"Could" being the operative word.

I was referring to a scenario where you have the same mosfets with the same quality but more phases in the VRM assembly. Given the same current/voltage each mosfet should dissipate less heat individually hence achieving safer operation.

I think you better clarified your statement when you qualified it with,

However it is not that simple , the quality of the VRMs themselves matters a lot too.

 

[Rehmanpa]

Is there a big difference between an 8 and 12 phase vrm? Idk how it's measured or what's considered good or not.

 

[EarthDog]

Is there a big difference between an 8 and 12 phase vrm? Idk how it's measured or what's considered good or not.

It depends on the quality of the parts. On intel mainstream platforms, it didnt matter much, the count. On x299 it matters a lot more.

Is there a specfic question in here or just generally talking vrms?

 

[dorsetknob]

more Phase's are generally considered Better and hence their appearance on higher end performance motherboards ( and Of course more Expensive)
As Said Before they generaly enhance Stability and the potential for higher overclocking

 

[Rehmanpa]

It depends on the quality of the parts. On intel mainstream platforms, it didnt matter much, the count. On x299 it matters a lot more.

Is there a specfic question in here or just generally talking vrms?

I meant 11 phase not 12 phase, sorry for the typo. I was comparing the asus Zen something ($550) and asrock ($450ish) professional gamer x399 motherboards and I was wondering if the power phase being higher on the asrock made a difference over the asus.

 

[bug]

I meant 11 phase not 12 phase, sorry for the typo. I was comparing the asus Zen something ($550) and asrock ($450ish) professional gamer x399 motherboards and I was wondering if the power phase being higher on the asrock made a difference over the asus.

It's more complicated than that. The difference is there, but it's usually small enough that the CPU matters more. You can get more GHz out of a good overclocker and an 8 phase motherboard, than you can get from a poor overclocker and a 12 phase motherboard. Also if your PSU has a clean output, VRMs tend to matter less.
Personally, I believe 8+ is plenty. Just look at how they're positioned, how they're cooled. Having good airflow while not obstructing your other components is more important than having a couple VRMs more.

 

[EarthDog]

Also if your PSU has a clean output, VRMs tend to matter less.

Not really...i mean a crap psu will stress the vrms more, but a clu sucking power out of them matters more. Id rather less clean psu power with a more robust vrm than more clean psu power and less robust vrm when overclocking.

I meant 11 phase not 12 phase, sorry for the typo. I was comparing the asus Zen something ($550) and asrock ($450ish) professional gamer x399 motherboards and I was wondering if the power phase being higher on the asrock made a difference over the asus.

for ambient overclocking, it wont matter. That said, find some reviews and see if they list the parts. Pretty sure the asrock is IR3555...

 

[bug]

Not really...i mean a crap psu will stress the vrms more, but a clu sucking power out of them matters more. Id rather less clean psu power with a more robust vrm than more clean psu power and less robust vrm when overclocking.

I didn't mean that VRMs become useless. Just that they're meant to smooth out voltage and if the PSU does a good job with that, there's less left for VRMs.

 

[Aquinus]

Depends on the MOSFETs being driven. Think of it this way, VRMs basically are switches. They take the 12v input from the PSU and steps it down to something usable by the CPU. To do this, the MOSFETs are (generally speaking,) turned on when the output voltage drops below a certain point and gets turned off when it goes above a certain point. This is the basis for a switched mode power supply. Heat usually scales to the switching frequency of the MOSFETs (when the transistors are between an on and off state, they briefly act like a resistor). Higher switching frequency usually translates to higher temperatures and lower efficiency but, results (usually,) in more stable voltages because the VRMs react faster to change. Doubling the number of phases can spread out those switching events which will reduce the amount of heat (or rather, spreads the heat out.) Also if the same quality transistors are used, it also means (usually,) that the VRMs are capable of outputting more current.

A great example is how (at the time,) the ROG boards have had 8 CPU power phases but, my P9X79 Deluxe has 16 but the ROG board is a better overclocker. The reason really boils down to the VRMs themselves, not the number of phases however, I can say that even at relatively high loads, the VRMs on my board stay relatively cool.

So the general case is that more phases usually means better power delivery however, that's not always the case. When you're talking about budget boards though, a 4 phase VRM setup will almost always be inferior to an 8-phase setup.

 

[Bill_Bright]

or rather, spreads the heat out.

I am glad you added that part for that is key.

Still, I agree with the comment earlier that a cleaner power supply that already has great regulation will put less strain on the VRMs. But because the PSU outputs +12V, +5V and +3.3V and motherboards and mounted devices use other voltages, 1.5V for example, dividing occurs too. And voltage division always involves some inefficiencies and requires some regulation which is also not 100% efficient. Inefficiencies in electronics is seen as wasted energy in the form of heat. Spreading that out to more devices adds more inefficiencies but at the same time, reduces the amount of heat any single device must endure.

So it is always a trade-off.

 

[EarthDog]

I didn't mean that VRMs become useless. Just that they're meant to smooth out voltage and if the PSU does a good job with that, there's less left for VRMs.

I didn't say they were useless. Nor did I infer it.

That aside, again, less stress, but they still need to be robust for the CPU which is taking the power. I'd rather have a less clean 'signal' from the PSU and a more robust VRM, than a cleaner 'signal' from the PSU and less robust VRM. There are two rooms to that party... one is needed more than the other.

 

[Aquinus]

Either way, efficiency goes down the hole the more times the VRMs have to either switch on or off because, the transition is where resistance is rising and that is where efficiency is lost. There are only two solutions to this problem:

1. Switch the VRMs less often (from on to off or off to on.)
2. Make the VRMs transition between states faster.

So, even on a board like my P9X79 Deluxe, not all 16 phases are used unless the BIOS says to use them or if the CPU demand is great enough to warrant using the extra phases to dissipate the heat more evenly however, running more phases means more VRM transitions (because you're adding more VRMs by using more,) and even at the same draw, can be less efficient than just using say, 4 or 8 of them in low power situations like idle and all of them in high power situations like when the CPU is boosting. More phases is not more efficient but, it's more capable of maintaining stable voltages at high current draws.

 

[delshay]

Well I have being looking at resistance value at each phase. This is to change the value to better precision, other than being a few fractions out. This has worked on my GFX card where it is more stable clock when overclocked. I have yet to see any effects on CPU when this is done on the motherboard.

This effectively is fine tuning each VRMs phase. It's still early to say what's going on here (on going project).

 

[Rehmanpa]

Either way, efficiency goes down the hole the more times the VRMs have to either switch on or off because, the transition is where resistance is rising and that is where efficiency is lost. There are only two solutions to this problem:

1. Switch the VRMs less often (from on to off or off to on.)
2. Make the VRMs transition between states faster.

So, even on a board like my P9X79 Deluxe, not all 16 phases are used unless the BIOS says to use them or if the CPU demand is great enough to warrant using the extra phases to dissipate the heat more evenly however, running more phases means more VRM transitions (because you're adding more VRMs by using more,) and even at the same draw, can be less efficient than just using say, 4 or 8 of them in low power situations like idle and all of them in high power situations like when the CPU is boosting. More phases is not more efficient but, it's more capable of maintaining stable voltages at high current draws.

Thank you for the information. So basically it's just marketing to try and get the average consumer to say, "it has higher vrm, must be betta!" So the VRMs I guess as long as it's above like 8 is fine?

 

[Gasaraki]

That's not a given. As you correctly noted, quality matters, as does case cooling. Generally, it is all about cleaner/stable power - especially with higher clock rates. Heat dissipation, while critical, depends on other factors besides the number of phases.

More phases means that the power is split up over more VRMs so the heat in each is lower with means the heat is spread out over a bigger area. The big VRM heat sink will be cooler than a small VRM heatsink.

So yes, more phases generally mean cooler.

 

[Aquinus]

Thank you for the information. So basically it's just marketing to try and get the average consumer to say, "it has higher vrm, must be betta!" So the VRMs I guess as long as it's above like 8 is fine?

Depends on the board and the MOSFETs themselves. Some MOSFETs can move a ton of current effectively while others are just trash. 8 phase VRMs are usually a safe bet but, that really depends on what components are used in the VRMs.

 

[FreedomEclipse]

I keep telling myself that it's just a phase im going through

 

[bug]

I keep telling myself that it's just a phase im going through

See? You should be going through 8-12 phases, otherwise there's too much stress on you.

 

[FreedomEclipse]

See? You should be going through 8-12 phases, otherwise there's too much stress on you.

Im just a vrm phase of emotion

 

[Bill_Bright]

Thank you for the information. So basically it's just marketing to try and get the average consumer to say, "it has higher vrm, must be betta!"

No, it is not "just marketing". More phases certainly can mean better quality power if quality parts, quality design, and quality assembly (soldering techniques and lead terminations, for examples) are employed too. And in this case, it may very well be worth the extra costs and the extra marketing that touts those advantages.

But if low quality parts are used in a poor design with shoddy assembly techniques and the extra phases are over-hyped on the motherboard box, then it might be just marketing "fluff". But that's where you do your homework and research the review sites (not "user reviews" but real, technical review sites) and those products that are more hype than substance will quickly be revealed and sorted out.