+12 V with 30 A = Good PSU?

hello,


There are so many PSU's when I went to buy one and when I found that Corsair 450 W wasn't available (live in India) . The main reason I'm buying a new PSU because when I returned my friend his UPS my PC started shutting down if I played games like COD4. With the UPS it very rarely shutsdown.

But anyway my question and doubt is if a +12 v rail has 30 A then can I assume I've got a good PSU in hand?
19 answers Last reply
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  1. Having the amperage you need won't guarantee the quality of a psu.
    Let the forum know what is available to you and you'll get reccomendations.
  2. I don't understand the concept of the rails...

    The GTX 260 needs 36A on the +12V rail.

    If a PSU has +12V1 = 17A, +12V2 = 16A, does that mean it is 33A rated?
  3. The GTX doesn't need 36 amps on it's own, it's reccomended to have a psu that can provide 36 amps to the entire system the card will be installed in. ( We have a member here who runs dual 260's on a 34 amp psu )
    Very rarely does adding the rails equal the total output.
  4. No. Multiple +12V rails are usually a single rail that has been divided with current limiters. In the above example, the total +12V amperage could be as low as 24A, but each individual pseudo-rail has been limited to a lower amount, in this case 17A or 16A. Usually (but not always), the label will state combined maximums for the various rails.
  5. I wouldn't. Their Greatpower line is supposedly better, but the first thing I saw about that one is it has a little red voltage switch, indicating an older design that is inefficient and doesn't include Active PFC. It is probably overrated as well, so I just wouldn't trust it. Oh, last answer to t3nchi; please start your own thread instead of hijacking this one.
  6. I mean no disrespect to the OP, but the problem might not be with the PSU. If it worked well with the UPS and not now, you probably have dirty power. Voltage spikes and lulls can cause havok with a computer. You might need to get a UPS of your own if you do have dirty power.

    Others have hit on your quality question. I would only add that amperage alone doesn't tell you if its a quality PSU, just like watage alone doesn't do the same thing.
  7. Two comments:
    1. A GTX260 only needs around 11 amps for itself. A good PSU, such as a 400 watt Corsair or something with similar specs, will power a "typical" system.

    2. The XClio that you linked to, in addition to no active PFC and the 70% efficiency, does not have overload protection on the 12 volt line.
  8. The table that I copied for a reference (note to self: include URLs in future references) shows a GTX260 (896MB) using 15.9A at full load. The similarly ranked HD4870 uses 12.6A at full load.
    Oh, and 4745454b is quite right (sorry to have been distracted by the hijack). If the power is really bad, you should get a UPS yourself; I'm thinking the one you borrowed probably has line regulation (sometimes called "AVR") also, which is what you want.
  9. Quote:
    No. Multiple +12V rails are usually a single rail that has been divided with current limiters. In the above example, the total +12V amperage could be as low as 24A, but each individual pseudo-rail has been limited to a lower amount, in this case 17A or 16A. Usually (but not always), the label will state combined maximums for the various rails.



    SO right now I have one 6 Pin connector coming right from the SMPS and is connected to the 4850. What do you think the Amps on that would be? 17A or combined of both 17A + 16 A . And why the hell are they splitting it. If the 12v Rail was one I would get more than 30 A


    And are the +12 v Rails meant to power the PCI-Express ?


    Quote:
    I mean no disrespect to the OP, but the problem might not be with the PSU. If it worked well with the UPS and not now, you probably have dirty power. Voltage spikes and lulls can cause havok with a computer. You might need to get a UPS of your own if you do have dirty power.


    What you said was possible. But it also happened when I had the UPS , but only less frequently. But without it just entering and playing COD4 for 1 Min would crash. I even have to play Fifa 08 at 1024x768 . even so random crashes happen. But never when I used Windows.


    So after all the advice , I have an eye on Corsair 450 VX Series which has 33A . Please help me if this is the right one.I'll even post the link for you guys

    http://www.corsair.com/products/vx/default.aspx

    I don't have a lot of money , so I can spend only when I have to. The Corsair PSU costs 4000 Indian Ruppes(1$=almost 50Rs). But I also have seen a Zebronics PRO series 500 W PSU which costs 3000 Indian Rupees.

    http://www.zebronics.net/Platinum_Powersupply.asp


    I have to admit I'm too dumb to choose a PSU , please HELP me this one time with the info from the two links so that I will have a good idea of what kind of PSU to buy with your suggestions.
  10. The Corsair is an excellent choice. Based on an old listing, Zebronics is garbage. Get the Corsair. It is reviewed here: http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story&reid=64.
  11. hash said:

    And why the hell are they splitting it. If the 12v Rail was one I would get more than 30 A

    And are the +12 v Rails meant to power the PCI-Express ?


    Actually, 30 amps total (not 33 amps) is probably an over estimate. I have an Antec 650 watt Tri-power. It says it has three 19 amp rails. True. You can draw up to 19 amps from any particular rail. But, the total you can draw is 52 amps.

    You split the rails because according to ATX 2.2 specs, each rail is limited to to 20 amps. So there are quite a few most excellent power supplies with single 12 volt rails (Corsair and PC Power & Cooling come to mind) that technically violate the specifications.

    Yes. the PCI-e power connections draw 12 volt power. Look at the PSU cabling. The yellow wires provide 12 volts.

    Get the Corsair. It's worth the price difference.
  12. Onus said:
    The Corsair is an excellent choice. Based on an old listing, Zebronics is garbage. Get the Corsair. It is reviewed here: http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story&reid=64.


    +1. Definitely go for the Corsair :D
  13. Funny thing is, I purchased a 600w UPS (Sorry guys I mentioned it as PSU previously) yesterday and the shutdown's that happened right after I enter games with high GPU usage ....STOPPED!!

    Is my UPS supplying extra power when the PSU goes on Full load? I don't know if its safe to continue this way. because without the UPS it shutsdown immediately I enter games like COD4.
  14. How much power can the UPS provide? I doubt it, but perhaps you have a small UPS that can only supply 300W. Once your card kicks in and your system wants 400W, the UPS will shut everything down. A UPS don't supply extra power, but conditions it so its clean, and provides you with back up power to safely shut equipment down should you lose power.

    You also might have a faulty UPS.
  15. Your message is ambiguous. The shutdowns have stopped? Or they've stopped in everything but COD4? What PSU did you buy? "600W" doesn't sound like a Corsair.

    Does the new PSU have a little red voltage switch? If it does NOT, it is "full range," able to adjust to a wide range of input voltage. Your mains might be low. What is it supposed to be? If 120V, maybe you're only getting 105V; if 240V, maybe you're getting 210V. Low input voltage puts more stress on a PSU. If the UPS you borrowed has AVR, it may be able to correct for that, boosting the input voltage to what it should be.
  16. Quote:
    Your message is ambiguous. The shutdowns have stopped? Or they've stopped in everything but COD4? What PSU did you buy? "600W" doesn't sound like a Corsair.


    Very Very Sorry, I made a mistake. I did not buy a new PSU , I bought a new UPS(600watt).

    To be more accurate this is what happened but stopped by a UPS which isn't even in the list of solving my problem but does! :non:

    With my previous PSU the computer shutsdown(Full power off,all fans go off) when I "ONLY" use Graphic Intensive application's. Otherwise it works without a flaw when I'm in the desktop listening to music or watching movie etcc... So from that I came to conclusion that my PSU was dying at full load of the ATI 4850. The PSU is a 450 Watt +12v 16A and +12v 17A.


    But all this happened only after my friend took his UPS back again(400w).Before he took his UPS shutdowns only happened very few times (maybe like after 5 hours,sometimes , never until I log out). Without the UPS just entering into a mission in COD4 or even fifa09 after 5 Minutes crashes it. So I went out and bought a 600 Watt UPS(Line Interactive) the brand is quite good with equivalent to APC(Costliest available here). And yesterday when I fired COD4 with all settings maxed out and played for more than 2 hours , No Shutdown works smooth.

    So, its just a little confusing for me whether I have to go out and buy another Corsair 450watt when all my problems are solved with a mere UPS or am I risking my components this way?
  17. Very likely your new UPS is providing a boost to your mains voltage. For this to be all it takes to prevent your PSU from shutting down suggests it is running right on the ragged edge, which may also describe how its waveforms look (e.g. ragged, possibly dangerous to attached equipment). While the UPS is a good idea, it sounds like it would really be best for you to get a quality PSU also. I still think you should get the Corsair VX-450.
  18. Thank you very much for all your help guys. I can't believe how much I've learned from Tom's hardware. :wahoo:
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