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# |Solved| Misleading PSU specs... - Page 3

### Poll Results: And the best PSU is...

Poll expired: Mar 22, 2008
• 14% (5)
Corsair TX650
• 60% (21)
PC Power & Cooling Silencer 750
• 20% (7)
• 5% (2)
Don't upgrade and continue to suffer!
Quote:
 Originally Posted by Sparhawk If you look closely my PSU is designed with two 12V rails supplying 20A each. Further down the page it mentions that the total power of the 12V rails together supply 336W only with the 5V and 3.3V rails added does the PSU meet the 550W spec.
Just a comment about this, because I find it odd. The spec page *claims* to give 2x 20A 12v rails, but then says those rails can only output 336W? Let's look at some calculations...

20A x 12V = 240W
240W x 2 = 480W

Technically, if those rails really are outputting 20A each, they should be giving 480W of 12V power. So which calculation is wrong on their website? Not sure, but I suspect that the 20A may be the actual maximum power draw after efficiency has been weighed in?

If we convert the 336W back to amps, here's what we get:

336W / 2 = 168W
168W / 12V = 14A

Interesting how comes out to an even amperage.... At any rate, that is your REAL amperage available on each of your 12v rails of your current PSU.

And a final note: 14A / 20A = .7 = 70%, which is a typical percentage of efficiency for a low-end PSU.
Quote:
 Originally Posted by sccr64472 OCZ doesn't make power supplies either. They're simply a rebrander just like Corsair.
Admitted and agreed, previously made by the same people who made EPower (relabeled older style OCZ's) and a few others, GE?
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Quote:
 Originally Posted by lenzo Admitted and agreed, previously made by the same people who made EPower (relabeled older style OCZ's) and a few others, GE?
FSP/Forton make their GamerXStream and StealthXStream models.
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Quote:
 Originally Posted by lenzo Admitted and agreed, previously made by the same people who made EPower (relabeled older style OCZ's) and a few others, GE?
Fortron (FSP)

Edit: Bah, Duckie you type too fast =P
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Quote:
 Originally Posted by SgtSpike Just a comment about this, because I find it odd. The spec page *claims* to give 2x 20A 12v rails, but then says those rails can only output 336W? Let's look at some calculations... 20A x 12V = 240W 240W x 2 = 480W Technically, if those rails really are outputting 20A each, they should be giving 480W of 12V power. So which calculation is wrong on their website? Not sure, but I suspect that the 20A may be the actual maximum power draw after efficiency has been weighed in? If we convert the 336W back to amps, here's what we get: 336W / 2 = 168W 168W / 12V = 14A Interesting how comes out to an even amperage.... At any rate, that is your REAL amperage available on each of your 12v rails of your current PSU. And a final note: 14A / 20A = .7 = 70%, which is a typical percentage of efficiency for a low-end PSU.
Did I say this comes up four times a day? Maybe five times a day?

In case you missed it.....

The "per rail" rating IS NOT a rating of power capability. It is a designation of at what current the power supply will shut down. Multiple +12V rails, in most instances, are NOT multiple +12V rails. They are a single +12V rail split up into multiple +12V rails each with a current limiter, called an OCP (for Over Current Protection) that will shut down the PSU if exceeded. So, as I said before, the number you see below +12V1, +12V2, +12V3, etc. on the label is just telling you what the OCP is set for on each circuit branch. This is why they can not be added up. This is not misleading. It's just a fact. The number below this, or the "combined maximum output" number, is the actual +12V output capability of the PSU.

We're talking two things with these: OCP rating and PSU capability. They're two different things and mathamatically can not be equated to each other.

Quote:
 Originally Posted by sccr64472 OCZ doesn't make power supplies either. They're simply a rebrander just like Corsair.
Well, to be fair most PSU "rebranders" do a bit more than slap a label on an existing product. The "rebrandeders" have their own engineers and R&D guys, etc. and have a lot of input in the finished product. Corsair probably has one of the best teams I've seen. Bested probably only by PCP&C (the original brand and now division of OCZ, but not necessarily OCZ as a whole). For example: Corsair may use a S12 PCB, but a good number of the components used and therefore specs are quite different than an actual S12.

Quote:
 Originally Posted by lenzo Admitted and agreed, previously made by the same people who made EPower (relabeled older style OCZ's) and a few others, GE?
NOT FSP. Come on guys. There's a quiz later.

EPower IS Topower. It's their American division. And the old ModXStream, PowerStream, etc. were all made by Topower.

Most of the CURRENT OCZ stuff (not PCP&C, but GameXStream, StealthXStream, etc.) is, as DuckieHo points out, FSP. If it's not FSP, it's 3Y, like the ProXStream. But 3Y is a division of FSP now anyways.
ive come to notice they look exactly the same int he past 2 months or so good thing i told my friend to buy it. Anyways i would go for the DA750 or if that too expensive go for the DA700 which has a MIR and the final price is the same price as the DA650. the 700w 68A single rail PSU will allow you to run a quad and your 3870's in CF
Quote:
 Originally Posted by kazakia ive come to notice they look exactly the same int he past 2 months or so good thing i told my friend to buy it.
Use the quote function so we know what "it" is.

Did we ever find out that the OP even really NEEDS a new PSU???

I believe he swapped out the RAM and now the PC is working fine????
Quote:
 Originally Posted by jonnyGURU Did I say this comes up four times a day? Maybe five times a day? In case you missed it..... The "per rail" rating IS NOT a rating of power capability. It is a designation of at what current the power supply will shut down. Multiple +12V rails, in most instances, are NOT multiple +12V rails. They are a single +12V rail split up into multiple +12V rails each with a current limiter, called an OCP (for Over Current Protection) that will shut down the PSU if exceeded. So, as I said before, the number you see below +12V1, +12V2, +12V3, etc. on the label is just telling you what the OCP is set for on each circuit branch. This is why they can not be added up. This is not misleading. It's just a fact. The number below this, or the "combined maximum output" number, is the actual +12V output capability of the PSU. We're talking two things with these: OCP rating and PSU capability. They're two different things and mathamatically can not be equated to each other.
Interesting... thanks for clearing that up, I was confusing myself. So a single rail is much better to have than dual rails, just because you know how much power you have available to you?
Yeah, my problem seems to be fixed. I really thought it was the PSU because the timing of the crashes seemed random. It turns out is was really just some bad ram sticks. Not initially bad but they would heat up like nobody's business and would give errors once hot.

I've got non-tracer versions of the BallistiX ram and they run cooler and faster (...so far).

If I do ever upgrarde my GPU I'll probably upgrade to the PC Power and Cooling Silencer 750 because it supports more GPUs(more PCI-E cables) than the Corsair one does. ATM I'd be hard pressed to notice a difference between my PSU and a more powerful one.

Also I'm behind a very good UPS which stops over and undervoltage to the PSU so I'm not too worried about the quality of the PSU. Although my 3.3v rail runs a little on the high side at about 3.42-3.44v. ...I can also run my computer under load for about 10-20minutes without power.
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Quote:
 Originally Posted by SgtSpike So a single rail is much better to have than dual rails, just because you know how much power you have available to you?
Well.. you shouldn't have to worry about it at all... ever... non issue. That's because a competent engineer and/or product manager should have spread the connectors out so there is plenty of power on a rail for any and all connectors attached to that rail.

Take, for example, this BFG:

http://enthusiast.hardocp.com/image....pfM180X2wuanBn

You've got 22A, 22A, 36A, 36A.

For explaining this easily/quickly, I'll just focus on the +12V3 and +12V4. The rails are limited to 36A each. That's 432W. These two rails provide power to the four PCIe connectors; two each rail. One PCIe is 6-pin, delivering up to 75W per spec, and the other PCIe is 8-pin, delivering up to 150W per spec. That's a total of 225W. That means the rail can deliver almost twice what the connectors are actually designed to deliver. So... would the fact that this PSU has multiple +12V rails have any effect on anyone? Not at all.

So why bother with splitting up +12V rails?

Well.. have you ever plugged a connector in backwards or heard of anyone that has? The floppy power connector in particular is very easy to plug in backwards, whether it's plugged into a floppy drive, Audigy card... whatever, it happens and it happens often. Well, short circuit protection should shut down a PSU. If you touch a hot lead to a ground the PSU should shut down right away. But if you put some resistance in that circuit, like in the form of a sound card or floppy drive, the PSU doesn't see a short. It sees a big load. If this load is allowed to run without limit, the wire heats up, the insulation burns off and you end up with a heap of melted plastic at the bottom of the case. With a current limit, the load caused by the short exceeds the current limit and shuts down the PSU preventing the wire to ever get hot enough to start a fire. And that's ALL it does. So if someone tells you they're getting better OC's with a single +12V rail PSU, ask them for their eye color because they may be full of something. On the flip side, if someone tells you that voltages are more stable because they have multiple +12V rails, they're full of it too because typically the split rails come from the same source and the circuitry doing the splitting isn't doing any kind of regulation or anything that would actually make the voltages "more stable."

Hope this helps.
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