Enermax Plaitmax EPM850EWT

[Zachboy]

Hi all, just some questions regarding this PSU that I bought for $300, a few weeks ago, and intend to use it on my next gaming rig(I'm just buying little bits and pieces at a time and eventually when I have a complete set, I'll start putting it all together )...so far I've only got two in my head(more may come in time....):

- On the specifications of the PSU, it states it has four rails of +12 line and all does 30A at max (I would guess), but total watts underneath it says otherwise; 840W at 70A....Am I mistaken? Shouldn't it be 120A? because there's four rails and four times 30A = 120A? ...but that *would* mean total wattage be 1440?
- Nowhere (not on the box or on the actual PSU itself) does it say it's *certified* for nVidia SLI or AMD/ATI CrossFire, so I am going to presume that this PSU isn't designed for SLI/CF?:hmm:

This probably a question that's already been asked here before and or me not *understanding* whatever said posts in threads on this forum and other areas....:\

Thanks in advance, Zach.

Oh yea, just realised I spelt the brand and model name wrong; please dis-regard as I can no longer edit my thread title....

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[lehtv]

Each of the four rails is capable of 30A independently, but the combined +12V load is 70A. E.g. in theory you can have 30A+30A+5A+5A, or 17.5A+17.5A+17.5A+17.5A before over current protection kicks in and shuts the PSU down. But in practice you will never load any of the rails anywhere near 30A (equal to 360W) so as far as usability is concerned you can think of it as a single 70A +12V rail.

SLI certification costs money, it's cheaper for them not to certify it. Crossfire certification doesn't cost anything, it's not really a certification at all. It still works with SLI and Crossfire just fine because of the strong +12V output - that's all that matters.

 

[Zachboy]

Each of the four rails is capable of 30A independently, but the combined +12V load is 70A. E.g. in theory you can have 30A+30A+5A+5A, or 17.5A+17.5A+17.5A+17.5A before over current protection kicks in and shuts the PSU down. But in practice you will never load any of the rails anywhere near 30A (equal to 360W) so as far as usability is concerned you can think of it as a single 70A +12V rail.

:\Hmmm.... So I *apparently* can only get up to 70A of total usuage of all the +12v rails? - Interesting....and I had thought the PSU's four rails can make the 30A limit together, regardless of Wattage the PSU can handle...

SLI certification costs money, it's cheaper for them not to certify it. Crossfire certification doesn't cost anything, it's not really a certification at all. It still works with SLI and Crossfire just fine because of the strong +12V output - that's all that matters.

Oh, so PSUs *don't* have to be certified to be SLI/CF ready; provided that they have strong +12v rail(s)? ...and how *strong* a +12v output would you say is the minimum? I'm curious...

Very good reply, Lehtv.:thumbsup:

Oh, another question popped up into my head: I remember reading something... from Hardware Secrets(Aha, I remember what it was and where it was from! Hehehe...^_^): [FONT=&quot]http://www.hardwaresecrets.com/printpage/Enermax-Platimax-850-W-Power-Supply-Review/1491[/FONT] Here's the quote:

[FONT=&quot]For a better load distribution, we recommend that you do not use the red connector that is connected to the +12V4 rail.[/FONT]

Anyone mind explaining that to me? I was going to start at that end for one of my dedicated graphics card and then go to rail 2(because I only intend to do only dual-SLI for the time being....), leaving rail 1 for the CPU and the motherboard and rail 3 for the peripherals....but after reading that, I got confused....

I just realised:

[FONT=&quot]The four +12 V rails are distributed as follows:[/FONT]

• [FONT=&quot]+12V1: ATX12V/EPS12V connectors and the main motherboard cable[/FONT]
• [FONT=&quot]+12V2: The red modular cabling connector that is the closest to the black connectors and the black connectors closest to the red connectors[/FONT]
• [FONT=&quot]+12V3: The middle red modular cabling connector and the black connectors that are the farthest away from the red connectors[/FONT]
• [FONT=&quot]+12V4: The red modular cabling connector that is the farthest away from the black connectors and the video card power cables that are permanently attached to the power supply[/FONT]

Wait, what? - Is this person trying to say that rail 4 is *the* rail that's used to supply power for the 6+2 pin PCIE connector that's permanently attached on the PCB? Okay, now I'm confused; the PCIE 6+2 power connector is actually *supplied* by rail 4? So there's no need to attach another modular cable to rail 4 and use that for the graphics card? So I can just use the one that's already hard soldered into the PCB, since that's on rail 4 and my intention was to use rail 4 and 2 (I just need to add a modular cable to rail 2 to output a PCIE 2+6 power connector for the graphics card) for the two graphics cards in SLI mode? Well, if that's the case - that defeats the purpose of having a *spare* rail 4 +12v line port on the PSU....

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[lehtv]

Oh, so PSUs *don't* have to be certified to be SLI/CF ready; provided that they have strong +12v rail(s)? ...and how *strong* a +12v output would you say is the minimum? I'm curious...

Well, a good rule of thumb for determining how much GPU a particular unit can handle is to look at the number of PCIe connectors it's supplied with. For example, if it has 2x6-pin PCIe connectors only, as is default for 500W units, it can handle a single graphics card that requires two 6-pin connectors, or two graphics cards that require one 6-pin each.

But sometimes units have less connectors than they're actually capable of powering within limits of reasonable safety and longevity. I think a good example is the Corsair TX650 V2 which only comes with two PCIe connectors by default despite being just as powerful as several other Seasonic-made 650W units that come with four connectors (XFX 650W and NZXT 650W for instance). In this case you could safely use molex to PCIe adapters for the second graphics card.

So it really depends on what cards you're going to be using in SLI or Crossfire. Less power hungry cards will work fine with a 500W unit while other cards may need as much as 850W to be safe.

What you can also do is google a SLI of Crossfire review of a particular card. I'd recommend reviews by Anandtech, Guru3D and Techpowerup for the power consumption tests. They'll show you much power - measured at the wall so not adjusted for the power supply's efficiency - the cards will use in SLI during gaming, along with recommendations for what sort of PSU is needed to safely power them.

I just realised:Wait, what? - Is this person trying to say that rail 4 is *the* rail that's used to supply power for the 6+2 pin PCIE connector that's permanently attached on the PCB? Okay, now I'm confused; the PCIE 6+2 power connector is actually *supplied* by rail 4? So there's no need to attach another modular cable to rail 4 and use that for the graphics card? So I can just use the one that's already hard soldered into the PCB, since that's on rail 4 and my intention was to use rail 4 and 2 (I just need to add a modular cable to rail 2 to output a PCIE 2+6 power connector for the graphics card) for the two graphics cards in SLI mode? Well, if that's the case - that defeats the purpose of having a *spare* rail 4 +12v line port on the PSU....

It's not really clear to me what the rail distribution is like from the quote... I don't know what the red and black connectors are referring to. All I can say is thet Rail 1 provides power to the CPU and the motherboard, and Rail 4 has the fixed PCIe cables

 

[Zachboy]

Well, a good rule of thumb for determining how much GPU a particular unit can handle is to look at the number of PCIe connectors it's supplied with. For example, if it has 2x6-pin PCIe connectors only, as is default for 500W units, it can handle a single graphics card that requires two 6-pin connectors, or two graphics cards that require one 6-pin each.

Okay.:thumbsup:

But sometimes units have less connectors than they're actually capable of powering within limits of reasonable safety and longevity. I think a good example is the Corsair TX650 V2 which only comes with two PCIe connectors by default despite being just as powerful as several other Seasonic-made 650W units that come with four connectors (XFX 650W and NZXT 650W for instance). In this case you could safely use molex to PCIe adapters for the second graphics card.

Yes..but how can you tell *if* it's just as "powerful" as other 650watt PSUs? Do you just read and compare the specs?:\

Manufactures design their PSU with limited power connector cables for a reason....maybe they had a good reason to not have that many PCIE power connectors for the Corsair TX650 V2? Or did they just wanted to *strip* it down so the end user would have to spend more to use it's full capacity? - Wait, that could be one of the reasons....

What you can also do is google a SLI of Crossfire review of a particular card. I'd recommend reviews by Anandtech, Guru3D and Techpowerup for the power consumption tests. They'll show you much power - measured at the wall so not adjusted for the power supply's efficiency - the cards will use in SLI during gaming, along with recommendations for what sort of PSU is needed to safely power them.

Sure....

It's not really clear to me what the rail distribution is like from the quote... I don't know what the red and black connectors are referring to. All I can say is thet Rail 1 provides power to the CPU and the motherboard, and Rail 4 has the fixed PCIe cables

http://www.hardwaresecrets.com/printpage/Enermax-Platimax-850-W-Power-Supply-Review/1491 - under:
*Power Distribution*

...and you shall see where I got the quote from. So, from that and from you, it would appear that the "soldered" PCIE 6+2 power connector on the PCB is *actually* using rail 4 and not 1?

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[lehtv]

Yes..but how can you tell *if* it's just as "powerful" as other 650watt PSUs? Do you just read and compare the specs?:\

It's as powerful as the ones I mentioned (XFX 650W and NZXT 650W) since it's based on the same design from the same manufacturer and has the same amperage specs. Many other 650W units are less powerful based on their rail specs, few if any are more powerful.

Manufactures design their PSU with limited power connector cables for a reason....maybe they had a good reason to not have that many PCIE power connectors for the Corsair TX650 V2? Or did they just wanted to *strip* it down so the end user would have to spend more to use it's full capacity? - Wait, could be one of the reasons....

The TX650 is aimed mostly at single GPU users, and being their lowest wattage TX series unit that is not modular, having only two PCIe connectors is good for most users. Most don't need more and not having more helps with cable management. TX650 is Corsair's midrange PSU for midrange gamers.

Of course, this also means that SLI/Crossfire enthusiasts are directed to buying their more expensive TX750 and TX850 units. I don't think it's just greed on their part, it makes sense from the point of view that not all SLI/Crossfire setups can be handled comfortably by a 650W unit.

Their HX650 on the other hand does have four PCIe connectors, not because it's more powerful but because it's more expensive and modular.

http://www.hardwaresecrets.com/printpage/Enermax-Platimax-850-W-Power-Supply-Review/1491 - under:
*Power Distribution*

...and you shall see where I got the quote from. So, from that and from you, it would appear that the "soldered" PCIE 6+2 power connector on the PCB is *actually* using rail 4 and not 1?

Oh, now I get it. Yeah, Rail 4 supplies the two fixed-cable PCIe connectors. Since it also supplies the first red modular header, you shouldn't use that same rail for another video card, as advised by that review. Connect additional PCIe cables to the second or third red modular header.

Seems like a weird way to setup the rail distribution, I'd have expected the fixed PCIe rail to additionally power only peripheral (molex) connectors, SATA connectors and such - if any at all. It's actually quite possible to overpower the rail. Two graphics cards can easily use more than 30A.

 

[Zachboy]

It's as powerful as the ones I mentioned (XFX 650W and NZXT 650W) since it's based on the same design from the same manufacturer and has the same amperage specs. Many other 650W units are less powerful based on their rail specs, few if any are more powerful.

Alright....amps must be the same and wattage as well....same number of rails I would guess.....or total amperage for total +12v.....

The TX650 is aimed mostly at single GPU users, and being their lowest wattage TX series unit that is not modular, having only two PCIe connectors is good for most users. Most don't need more and not having more helps with cable management. TX650 is Corsair's midrange PSU for midrange gamers.

Uh-huh....

Of course, this also means that SLI/Crossfire enthusiasts are directed to buying their more expensive TX750 and TX850 units. I don't think it's just greed on their part, it makes sense from the point of view that not all SLI/Crossfire setups can be handled comfortably by a 650W unit.

Yeah...true....espicially high end to enthusiast graphics cards.......

Their HX650 on the other hand does have four PCIe connectors, not because it's more powerful but because it's more expensive and modular.

I heard there isn't much difference between "modular" and normal PSUs.....just the power cables are *detachable*, that's about it....also I heard that the connection isn't as good as cables that are hard *soldered* onto the PCB of the PSU....

Oh, now I get it. Yeah, Rail 4 supplies the two fixed-cable PCIe connectors. Since it also supplies the first red modular header, you shouldn't use that same rail for another video card, as advised by that review. Connect additional PCIe cables to the second or third red modular header.

Yes, now that makes sense to me! Thankyou!^_^

Seems like a weird way to setup the rail distribution, I'd have expected the fixed PCIe rail to additionally power only peripheral (molex) connectors, SATA connectors and such - if any at all. It's actually quite possible to overpower the rail. Two graphics cards can easily use more than 30A.

...I had thought that rail 1 provided power to the maotherboard, CPU and the graphics card if you use that power connector....never would have thought that it uses rail 4.....well, there's already a PCIE 6+2 power connecter, might as well use that for one of my GPUs as that's on a *different* rail to that of the CPU and motherboard....right; rail 2 and 4 is dedicated to my GPUs. Rail 3 will be dedicated to peripherals and...not sure what to do with the fourth rail port on the PSU.....I guess leave it out and not touch it at all as the *fixed* PCIE 6+2 power connector already draws power from that rail?

What were they thinking having *another* port for rail 4? There's already a *fixed* PCIE 6+2 power connector on that rail that you could use for your GPU(s)....that's interesting as it doesn't say on the box or even on the PSU itself.....hm...

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[lehtv]

I heard there isn't much difference between "modular" and normal PSUs.....just the power cables are *detachable*, that's about it...

That's exactly what modularity means

.also I that the connection isn't as good as cables that are hard *soldered* onto the PCB of the PSU....

Well not true, the power is delivered just as well from a modular interface. There's really no risk of "losing" the connection or receiving worse quality power

 

[Zachboy]

That's exactly what modularity means

Oh. ^_^ Less cables that aren't used means that the insides of the computer case will be more tidy!:biggrin:

Well not true, the power is delivered just as well from a modular interface. There's really no risk of "losing" the connection or receiving worse quality power

....:hmm: well, provided that they galvanise or whatever they do to protect the metal from corrosion and the like, I'm fine with it....^_^

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[BFG10K]

That 30A value is probably under-rated anyway. Most of the time OCP is set much higher, like 45A. For a quality multi-rail PSU with good power distribution, it’s almost impossible to overload a rail and make it trip.

As for modular vs modular, every test I’ve seen has shown negligible differences in power delivery performance.

 

[Zachboy]

Uh-huhhhh.....so I guess I'd get better return for, say a 2000 watt PSU...?

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[lehtv]

Make it 5000 Watt and you're safe