Power Supply Myths?

Discussion in 'Hardware Discussion & Support' started by Vampyromaniac, Apr 15, 2007.

  1. Grace

    Grace HH's Tomboy

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    That concept is correct. However, if (example) a 500W PSU can actually output 500W or if it can only draw 500W and deliver a 500W*efficiency % inside the system, depends on the manufacturer of the PSU. Most generic PSUs state their maximum power DRAW, not output. So a generic 500W PSU with 75% typical efficiency can output only 375W max. Tricky, isn't it?



    The Power Trio 550W PSU is superior by every aspect, I see no reason why not to get that one.
     
  2. DudeBoyz

    DudeBoyz banned

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    Here's a link to a nice Single 12v Rail Enermax that might be worth a look:

    http://www.newegg.com/Product/Product.asp?Item=N82E16817103437

    Enermax usually makes great stuff.
     
  3. DudeBoyz

    DudeBoyz banned

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    I don't get why having one 80mm fan at the back of the PSU and another 80mm fan at the bottom of the PSU to help draw air up from the CPU area

    Like the one in this pic here - up at the top left you can see there are two fans in the PSU:

    [​IMG]

    Why would that not be a good configuration?
     
  4. Grace

    Grace HH's Tomboy

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    There is no such thing as 'good' or 'bad' configuration. Each configuration is ideal in certain environments and ineffective in others.

    Zelig mentioned a single 80mm fan. That configuration is good, but not for powerful PSUs. It tends to be silent since the fan is inside the computer case and so the sound is lessened, but it is not the best possible method of cooling. This design is pretty much replaced now by the single 120-140mm fan design, which is still silent but moves a lot more air.

    You mentioned a dual 80mm fan design. This is good for cooling in general, but two 80mm fans are usually above-audible levels. It is real hard to make a silent PSU with 2 80mm fans which doesn't overheat and/or gets noisy after some load. Very high efficiency PSUs benefit from this design, but not all of them.


    Take into consideration that all PSU cooling configurations ultimately push the majority of the air they use for their cooling towards the rear of the case, no matter where the fans are placed.
     
  5. DudeBoyz

    DudeBoyz banned

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    That's a rather inflexible statement...

    Thankfully, some PSU's, like the one I have, provide the ability to adjust fan speed. Mine has a dial right on the back. :)
     
  6. Grace

    Grace HH's Tomboy

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    It may be, but it is correct. "Flexibility" is not something I'm concerned about. Nothing is perfect. All configurations serve the same purpose, which is cooling the PSU, but each of them has certain limits.


    Thankfully, the design of your PSU was dropped even by the company which invented it, because if you turn the fan down all the way and load the PSU due to the heat the efficiency and total output of the PSU will severely decrease and it will eventually shut down...barely at 70-75% of its rated full load. Also, running the PSU at higher temperatures will vastly affect the capacitor aging, which means that your PSU will not be able to output its rated power soon enough and as you can guess the lifespan is also severely affected. So, you have the ability to control the noise of your PSU, but you affect its performance at the same time. Wonderful, is it not?

    Sorry for not getting too technical on that, I have a limited amount of time to spare. :sigh:
     
  7. Matth

    Matth Flash Banner Hater

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    Just reminded me...

    Decent power supplies often have a "temperature controlled fan" - which varies speed according to the conditions.

    Cheap ones often claim to have a "temperature control fan" - after all, the fann (blowing full blast all the time) does do something to control the temperature, as it would be damn hot without it.
     
  8. Judas

    Judas Obvious Closet Brony Pony

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    I don't know, i think the concept of Dual Rails was pretty much in consideration for a Single Video card connection to feed it a fairly stable source of power, and the other rail was for everything else.

    Dual rails are horrid for setting up a performance power house of a machine, i ran into that dual rail issue with my OCZ 600 watt PowerStream whe attempting to run 2 video card (BAD BAD idea)

    Triple rails sounds dandy to, 2 video cards and the rest seperately handled.

    I think the whole concept of having multiple rails is to better provide Solid/Stable power to what it's connected to. I think it's also to prevent interferance. Multiple rails would be better suited for the Overclocker as well. Better stability, cleaner and less volitile power means higher overclocks.

    The whole fan placements and size ordeal is slightly moot, considering IF you were running a PSU at it's MAXIMUM capacity at all times, you'd be having issues anyways, if you running slightly below it, you'll probably eventually run into issue due to PSU deterorating over time. IMO, if anyone is going to get a PSU, figure out how much you need using a few of the PSU caculators out there and then put on another 25% at least for safe measures and with the possibility of upgradeing it down the road. (IMO)

    The modular issue, yes, the more connections you have, the more resistance you add, and the higher chance of something failing down the road as well.

    If a modular psu is built, a good quality one should still last YEARS before it's connectors wear. And considering that majority of the time, enless a conneciton is disconnected and reconnected and messed around quite frequently, this should be a problem really.

    The only thing that could be a potential issue is keeping the connection tight and solid, everytime a PSU is fired up, all the little screwed/pins/bolts whatever will physically move a bit, even while running depending on the sudden loads experience, a set of pins could be oventually pushed out simply by using it, but i'm seeing more modular psu with clips to hold the connectors in place much better then some of the loser standard slides.
     
  9. Grace

    Grace HH's Tomboy

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    Actually, it all started by giving a separate 12V rail to the 12V CPU power cable. They claimed that the power towards the CPU was 'cleaner', 'free of ripple' and the CPU was more stable like that. I cannot say I ever agreed to that.

    Also, no matter how many rails a PSU has, I never saw a single one feeding the 2 PCIe connectors from 2 separate 12V lines. Even 1KW+ PSUs offer a single line (usually the 3rd) to the PCIe connectors.
     
  10. HardwareHeaven

    HardwareHeaven Administrator Staff Member

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    I personally wouldnt touch a modular PSU for a variety of reasons. Also Judas, lay off the coke man, most of that post sounded like you were high or something, such a load of nonsense.
     
  11. mike2h

    mike2h New Member

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    ty z.
     
  12. Judas

    Judas Obvious Closet Brony Pony

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    I didn't think the 12v 4 pin connector was a seperate rail, thought it was just a MORE direct pipe to the CPU, or at least an additional less restricted pipe to it.

    So my OCZ GamerXstream, written on the side of it, stating 12v1/2/3/4 all having 18amps each, and considering that a x1900xtx at it's peak load, would require nearly the full 13-15amps? (average 11amp if what i've read is correct? )....

    Cause 2 cards wouldn't be able to feed of 1 rail, and i know it won't work with the powerstream 600 as the single 12v rail powering 2 x1900's would results in the PSU tripping the overload.
     
  13. mike2h

    mike2h New Member

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    you should have 2 cables - one labeled pcie1 the other pcie2. they go to each card & are on seperate rails.
     
  14. DudeBoyz

    DudeBoyz banned

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    Can't agree with you on that one.



    PSU's are adopting the same variable fan speed functions that video cards have. It slows down when heat is low, speeds up as cooling is needed.

    The dial on the back of my PSU does NOT allow you to turn the fans completely off - just provides you a range of RPM's from low to higher. Just like a regular fan controller.

    I'm finding that though you try to sound like an expert, some of your statements clearly show you are not. So, I think I'll spend my time reading other opinions from folks who allow for some level of "gray area" discussion on the subject and not pretending that they know more than everybody else might.
     
  15. Judas

    Judas Obvious Closet Brony Pony

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    just a recollection.


    the Voodoo 5 6000 was the first to require additional external power, i beleive this was before the P4 (12v) connection game in, WAY before.
     
  16. DudeBoyz

    DudeBoyz banned

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    I remember that too! lol...

    I should have kept my old Voodoo 5 5500 just for old times sake.

    I had the two 12 meg Voodoo cards that ran beside my old ATI card. Descent never looked so good, baby!
     
  17. Zelig

    Zelig Well-Known Member

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    IIRC, the 750 watt SilverStone Zeus PSU only has 1 PCI-Express connector on the +12V3 rail, it then has 1 on the +12V2, and 2 on the +12V4.

    Most problems I've seen with multi-rail desings hasn't been becuase of the actual multi-rail design, but in poor assignment of connectors to the different rails. Thankfully, this seems to be much improved.
     
  18. DudeBoyz

    DudeBoyz banned

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    My buds have found success by ordering very inexpensive adapters to convert Molex to SATA, SATA to Molex and stuff like that. You can do the same with PCI-Express connectors, can't you? My Sapphire X1950 Pro 512 meg AGP came with Molex to PCI-E (or vice-versa) adapters in the box. Did not need to use them though.

    Anyway...
     
  19. Grace

    Grace HH's Tomboy

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    I can't force you to, I simply don't care if you do either.


    Thermal controlled and manual controlled fans are a separate thing. You talked about manual controlled fans.

    I never said that you can turn it off; running it at the lowest possible speed when the PSU is heavily loaded is a far different thing from that.


    I'm finding out that you either cannot understand my statements, or that you simply try to twist them. And for your own information, I am an electronics expert and power electronics are my specialty. And I'm not about to debate about my knowledge and skills with someone like you. So, have a great day. :p
     
    Last edited: Apr 18, 2007
  20. Grace

    Grace HH's Tomboy

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    Not always, but all 2 rail PSUs have that cable separated as the 2nd rail and usually everything else is the 1st rail.

    Your 1900XTX has a 10A peak power; it can never draw more than 10.5A, or it's power regulation system will fail.

    That shouldn't happen, because when a rail is overloaded the rest of the rails will support it. So something else was wrong with your PSU.
     

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