OCZ/Enermax

[The Duke]

I was hoping someone could fill in a bit of information concerning hold-up times and voltage regulations for two PSU's. An OCZ 600W GameXtreme Power Supply w/ Quad +12V and an Enermax 535W EG565AX-VE FMA II. I've been to both websites and checked but neither listed the hold up time or voltage regulation for either card. Also, I know that OCZ is a quality product, but does anyone know what Enermax is like?

Another question I have is when someone says that you shouldn't settle for say any less than 32A with regards to a minimum requirement for a video card(s), is that 32A on one 12V rail, or a combination of the 12V rails whether there are 2 or 4? Is it the total number of amps regardring 12V rails that is important (as long as they aren't under 18A each) or does that 32A have to be carried on one rail only, even if there are multiple rails?

Any help would be appreciated.


Thanks,

 

[ceewi1]

I was hoping someone could fill in a bit of information concerning hold-up times and voltage regulations for two PSU's. An OCZ 600W GameXtreme Power Supply w/ Quad +12V and an Enermax 535W EG565AX-VE FMA II. I've been to both websites and checked but neither listed the hold up time or voltage regulation for either card.

The OCZ is rated for 5% regulation, but in practice should remain within 1-2%. Both units are rated for 17ms hold up time.

Also, I know that OCZ is a quality product, but does anyone know what Enermax is like?

Enermax is another quality brand, and this unit is no exception. I'd prefer the OCZ, though.

Another question I have is when someone says that you shouldn't settle for say any less than 32A with regards to a minimum requirement for a video card(s), is that 32A on one 12V rail, or a combination of the 12V rails whether there are 2 or 4?

This refers to the total output on the +12V rails. This cannot be found by simply summing the total output of the +12V rails. The total rated +12V output should be listed.

 

[Archangel]

The OCZ is rated for 5% regulation, but in practice should remain within 1-2%. Both units are rated for 17ms hold up time.

Maybe a stupid question.. what does the holdup time stand for? i know Pc PSU's are switching power suppies ,.. so is it the time it needs to regulate itself to the desired voltage?

 

[Mankz_91]

OCZ.... great PSU's....

 

[The Duke]

Thanks for the reply.

The total rated +12V output should be listed.

Unfortunately, that's a negative.

For the OCZ:

Output:
DC Output / Max. Output Current
+3.3V: 36A
+5V: 30A
+12V1: 18A
+12V2: 18A
+12V3: 18A
+12V4: 18A
-12V: 0.5A
+5Vsb: 3.0A
+3V & +5V Combined: 155W
+3V, +5V & +12V Combined: 580W
Total Power: 600W

This cannot be found by simply summing the total output of the +12V rails.

How does one go about figuring out the total output of just the +12V rails?

After doublechecking the PSU 101 thread, I found this section:

In the example above, there are two 12V entries each with 18A so we have a sumtotal of 36A available to the 12V rail.

All they have done is just add the two 18A together, no?


Archangel:

Maybe a stupid question.. what does the holdup time stand for? i know Pc PSU's are switching power suppies ,.. so is it the time it needs to regulate itself to the desired voltage?

From the PSU 101 Thread:

Hold-up Time
In an idea world, PSUs deliver nice clean power, 24x7x365 but in realiy that may not be the case and for very brief moments, there will be a flicker in power. The hold-up time rating of the computer indicates the duration that it can handle without power. Generally speaking 16s is standard with some exceptional power supplies being able to "pretend nothing happened" for up to 20ms and 24ms.

Thanks,

 

[Archangel]

the OCZ PSU's have a somewhat unique power table,. yes.. anyhow,.. they are able to deliver 18A max per rail.. the total power delivered cannot exceed 580W on them (even that wont be reached, since then the 3.3 and the 5V lines wouldnt deliver any power)

so... assuming the 3.3 and the 5V rails would be loaded to their max of 155W.. it would leave 425W for the +12V rails,. knowing that.. P = U*I => 425 = 12 * I => 35.4166A (35.5A) on the +12V rails,.. with 18Amp wich can be drained max per rail

Edit2: theoretically ^^

 

[ceewi1]

Maybe a stupid question.. what does the holdup time stand for? i know Pc PSU's are switching power suppies ,.. so is it the time it needs to regulate itself to the desired voltage?

Hold-up Time
In an idea world, PSUs deliver nice clean power, 24x7x365 but in realiy that may not be the case and for very brief moments, there will be a flicker in power. The hold-up time rating of the computer indicates the duration that it can handle without power. Generally speaking 16s is standard with some exceptional power supplies being able to "pretend nothing happened" for up to 20ms and 24ms.

Aside from the technical, there is a strong relationship between the hold-up time of a PSU and its general quality. A high hold-up time usually means a good PSU. It's also important when using a UPS (hold up time of the PSU should be significantly greater than the switch time of the UPS).

 

[The Duke]

Thanks ceewi1

so... assuming the 3.3 and the 5V rails would be loaded to their max of 155W.. it would leave 425W for the +12V rails,. knowing that.. P = U*I => 425 = 12 * I => 35.4166A (35.5A) on the +12V rails,.. with 18Amp wich can be drained max per rail

If that is the case, then what good is it having 4 +12V rails at 18A each? If 35A is all that is available, assuming the 3.3V and 5V rails are loaded, then 2 12V rails at 18A each (36A total) is all that is needed, right? What purpose do the additional 2 12V rails serve?


Thanks,

 

[Archangel]

well...its merely to divide the power more evenly, without pushing a rail to its full load (since that would generate more heat ) I also can immagine it runs a bit more stable, and having a heavy load device connected to 1 rail, wouldnt drop the voltages on the other rails

 

[ceewi1]

Archangel is correct about the OCZ GameXStream 600W having a maximum of 580W on the +12Vs.

Either the total Power output or total current output on the +12s should be listed, although it isn't always easy to find. If given the total power output, divide by 12 to get the total current output.

How does one go about figuring out the total output of just the +12V rails?

After doublechecking the PSU 101 thread, I found this section:

All they have done is just add the two 18A together, no?

That is often used to give a rough idea, but is rarely accurate, even with dual rail PSUs. With quad rail units, it's not even close.

If that is the case, then what good is it having 4 +12V rails at 18A each? If 35A is all that is available, assuming the 3.3V and 5V rails are loaded, then 2 12V rails at 18A each (36A total) is all that is needed, right? What purpose do the additional 2 12V rails serve?

For one thing, isolating the additional rails makes them less prone to voltage fluctuations. More importantly, you won't be loading any individual rail to its full extent. Let's say we had a dual rail PSU where +12V1 powered the CPU and motherboard, and +12V2 powered everything else (a common configuration), with the limitations you propose (35A total, 18A on each +12V). In a situation where 10A was drawn from +12V1, 25A would still be available, however only 18A could be drawn from the second rail, due to the individual rail limitation, leaving 7A unusable.

Worse still, if the total load on +12V2 on our hypothetical unit exceeded 18A, which is possible for a very highly loaded system, the PSU could fail, despite having a net 7A it could still provide. It's important to provide power where it's needed.

so... assuming the 3.3 and the 5V rails would be loaded to their max of 155W.. it would leave 425W for the +12V rails,. knowing that.. P = U*I => 425 = 12 * I => 35.4166A (35.5A) on the +12V rails,.. with 18Amp wich can be drained max per rail

It is important to realise that this isn't likely to occur. That sort of load on the +3.3V and +5V rails with a corrseponding load of only 35.5A on the +12V is unrealistic for a modern system. The unit must be designed to deliver more than this minimum on the +12Vs.

 

[Archangel]

thats why i said assuming the 3.3 and 5 V rails would be under full load
but yea.. i gues i should have mentioned thats highly unlikely to occur

 

[The Duke]

Let's say we had a dual rail PSU where +12V1 powered the CPU and motherboard, and +12V2 powered everything else (a common configuration), with the limitations you propose (35A total, 18A on each +12V). In a situation where 10A was drawn from +12V1, 25A would still be available, however only 18A could be drawn from the second rail, due to the individual rail limitation, leaving 7A unusable.

Worse still, if the total load on +12V2 on our hypothetical unit exceeded 18A, which is possible for a very highly loaded system, the PSU could fail, despite having a net 7A it could still provide.

Why would the 7A from the first rail be unusable? Are individual components, CPU or video card for example, only able to draw from one +12V rail and not both? Whereas, if there were 4 rails, V1 powering the CPU and motherboard, V2 and V3 could each power a video card, and V4 would account for everything else, correct? (Am I at least close? ) By the way, does the user have to specify how it wants the computer components to utilize the rails, or is it done automagically?

Is there a single component that would ever draw more than 18A?


Thanks

 

[Archangel]

Why would the 7A from the first rail be unusable? Are individual components, CPU or video card for example, only able to draw from one +12V rail and not both? Whereas, if there were 4 rails, V1 powering the CPU and motherboard, V2 and V3 could each power a video card, and V4 would account for everything else, correct? (Am I at least close? ) By the way, does the user have to specify how it wants the computer components to utilize the rails, or is it done automagically?

Is there a single component that would ever draw more than 18A?


Thanks

yea.. the OCZ PSU's have 2 rails for SLI/CF grafic's,. 1 for the motherboard+CPU and 1 for the optical's/HDD's iirc.

about specifying... Nothing it automatic.. its merely how you connect the cables. you cant configure a SPU sith software or so,. its just a 'dumb' piece of hardware

 

[ceewi1]

Why would the 7A from the first rail be unusable?

Because with only 10A capable of being drawn from +12V1 (i.e. all the CPU will pull at max load), and a max of 18A on +12V2 (current limitation), 7 of the toal 35A can't be applied anywhere. If the sum of the components on the +12V2 required some of that extracurrent ... no such luck.

Are individual components, CPU or video card for example, only able to draw from one +12V rail and not both?

Correct

Whereas, if there were 4 rails, V1 powering the CPU and motherboard, V2 and V3 could each power a video card, and V4 would account for everything else, correct? (Am I at least close? )

You're very close. The exact configuration differs somewhat between units. In the case of the GameXStream series, +12V1 powers the CPU, +12V2 powers the drives, fans, and pretty much everything else except for the video cards, and +12V3 and +12V4 each power one PCI-E connector (for the video card(s)). Notice that +12V4 is never used if you don't have SLI. This is an example of why the unit should be able to 'reallocate' that portion of the total current output to other +12V rails.

By the way, does the user have to specify how it wants the computer components to utilize the rails, or is it done automagically?

No, this is hardwired within the PSU. The user has very very limited control (e.g. could use a molex to PCI-E converter to run a video card off +12V2 (not that you would with this unit)).

Is there a single component that would ever draw more than 18A?

No, and if there was the majority of high end PSUs would be unable to power it.

 

[The Duke]

Cool. I think I got it. Thanks to both of you for the help.

On a side note, if the CPU and PSU both have their own fans, and assuming one does not wish to overclock anything, is an additional case fan necessary? Are there other components that tend to heat up? I know some video cards come with their own fans, but if a particular card does not, should an additional case fan be put in regardless?


Thanks,

 

[Archangel]

Not really nesecairy especially not if you dont overclock