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Does GPU-Z really state valid Current?

Discussion in 'AMD / ATI' started by RuskiSnajper, Sep 23, 2009.

  1. RuskiSnajper

    RuskiSnajper

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    I have HD4870 , And an Enermax Liberty DXX 620W PSU , I do not know if the PSU has real multi rails or there is split 1 rail. The PSU has 2 rails as stated.

    GPUZ says my gpu needs 23A , while each rail supports 22A , I don't know if the rails are crossing capable(so it won't overload the one) But I need to make sure cause I am experiencing problems (here, if you want to help http://forums.pcworld.com/index.php?/topic/66370-call-of-duty-4-freeze-bad-ram-unstable-machine/ )


    But the PSU manual suggests , both rails combined have 432W(36A)

    What does this 36W mean , some people and around are telling the rails are sum up?

    One other fact I have seem to never crossed the line, PSU never shutdown.
     
    Last edited: Sep 23, 2009
  2. W1zzard

    W1zzard Administrator Staff Member

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    the current is not @ 12 V
     
  3. PVTCaboose1337

    PVTCaboose1337 Graphical Hacker

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    [​IMG]

    Do the math...
     
  4. RuskiSnajper

    RuskiSnajper

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    Some said that HD4870 need 11amps; ?

    What math, the volt are withing the GPUprocessor , not the whole gpu.
     
  5. jagd

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    Enermax liberty 620w is a good psu and can power 4870 without problem .
    36a (=432w ) is maximum you can use from two +12v rails , if you use 22a from one rail you can use 14a from second rail .
    people having problem with GTA4 are you sure it is not a gta4 problem ,take a look here http://forums.techpowerup.com/showthread.php?t=104166
     
  6. RuskiSnajper

    RuskiSnajper

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    Thank You a lot for this explanation jagd, I am not a PC noob but I can firmy say somethings in the PC market are very confusing and never fully written what's all about ,not in the manual and sometimes hard to find.

    And I also discovered something from my PSU that's not same as in infinity , rails and modular jacks , my rails are very different , as a matter of fact it looks like the HARDWIRED mobo and CPU are using one rail , and the system(which all those modular jacks are for) are on the second rail only.

    I'll hope disconnecting some stuff like add. fans , DVDdrive ..etc


    While I still don't know if the GPU really uses 23A if that would be the case , and with all those hardware , why PSU didn't shutdown? Or maybe I am putting rails on heavy strain and the quality of the PSU is what is making it working? lol , And I know enermax is good yeah!
     
    Last edited: Sep 23, 2009
  7. jagd

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    single 4870 will use 15-16a (180w-192w max) , and your system specs shows 1 hdd and 1 dvd-writer + Q9300 @3ghz .
    Mail enermax for pci-e power cables and/or look to local pc/hardware forums for pci-e cables ,you may find someone who psu died but has cables if you are still looking cables .
    how long are you using 4870 and since when do you have this problem?did you look to link for gta4 problems

    rail distribution http://www.pcper.com/article.php?aid=442&type=expert&pid=2 it says +12v2 for 4+4 cpu connector and 12v1 is for rest
     
    Last edited: Sep 23, 2009
  8. RuskiSnajper

    RuskiSnajper

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    Right , so the GPUZ has false readings , also I will update my specs , new ram and no overclock.

    I will see what will enermax have to say when I , explain how I did not received them , they can also say it's my problem with the shop and they have nothing to do with it. If it's really a nice company , it will send me those spare ones :D
     
  9. ghost101

    ghost101 New Member

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    GPU-Z is not giving incorrect readings. The voltages are different from that of 12v rails.

    For example, if the gpu core is at 1.2v and draws 60A, then it is using 72w.

    Assuming 100% efficiency transforming of current thats 6A at 12v.

    Note: I don't actually know how PSUs change voltages, my basic physics knowledge tells me a transformer is needed, but that's irrelevant anyway.
     
    Last edited: Sep 25, 2009
    angelkiller says thanks.
  10. RuskiSnajper

    RuskiSnajper

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    So you are trying to say that the GPU PEAK is as high as 23A?

    I am talking about VDDC Current in sensors of the GPUZ to be precise.


    Well I tried to validate but , it doesn't include sensors ; anyways http://www.techpowerup.com/gpuz/cdmm8/
     
  11. ghost101

    ghost101 New Member

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    Yes. My HD 4890 core actually has 80A of current passing through when under intense load.

    Of course thats not at 12v, but only at ~1.3v.

    e.g.

    [​IMG]

    76.5A @ 1.3125v = 100.4W

    This is the core power consumption alone. You need to add the vram power consumption and any other components.
     
    Last edited: Sep 24, 2009
  12. RuskiSnajper

    RuskiSnajper

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    So the ... this is more complicated that I thought!

    The VDDC current that is stated in GPUZ is relative to the vcore and not 12V then.

    But one thing doesn't makes sense is that , this all is not mentioned or explained in the manual.


    http://www.pcper.com/images/reviews/442/7-12Voutputs-Table.gif


    I did not knew about this at all. As it appears , slight info for this is in the physical manual I have , it says Rail1 For system , Rail2 For Cpu ,

    So the CPU has a whole rail for him self , and everything else is on the other rail hmm..

    So if I use all of the 22A , this leaves the CPU with 14A , and if CPU needs for example only 10A , that 4A will be wasted?
    That's why I heard how singlerails are somewhat better at some points.


    EDIT: Thanks for the explanation. Now I get it.
     
  13. ghost101

    ghost101 New Member

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    A HD 4870 on the enermax 620w psu will be fine. Stop worrying.

    edit: I see you have the psu already. The psu may be faulty, but 36A on 12v rails is enough.

    edit2: I see that you think that "amps" may be wasted. But what the specs mean that 22A load can be put on any one rail at one time. But the sum cannot exceed 36A.
     
  14. RuskiSnajper

    RuskiSnajper

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    I did not know that when you lower the voltage , the amperage for that voltage becomes relative and not absolute to the total amperage at 12V

    Huh what a lesson.


    How about converting 75 @ 1.3 to ? @ 12V . Meh won't be so easy.

    A more understanable question would be: If I am using 75Amps while having 1.3Volts , how many amps will be used on the 12V of total

    That means what is the actual consumption of amps looking from 12V , as GPU needs 12V wires, is there any monitoring software for just this?
     
  15. ghost101

    ghost101 New Member

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    Don't know how old you are, but you would normally get taught this in school around ages 14-16 in physics.

    Power(P) = Voltage(V) x Current(I)

    So holding the power constant, any change in voltage must be matched by a change in current.

    This is what a transformer does across electricty grid systems. In the UK at least, you have to know how a transformer works for gcse science(age 16 exams).

    http://en.wikipedia.org/wiki/Transformer
     
    Last edited: Sep 24, 2009
  16. RuskiSnajper

    RuskiSnajper

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    Inded that I know 16year exams and W=AxV , but I didn't knew that you can have more Amps with less Volts. I thought these aren't actual amps like amps on 12V rail?

    I thought Amps v 1.3V are smaller that Amps v 12V. lol

    But what's the deal anyway , what would the sensor for measuring how many amps have been used on 12V rail

    This is very confusing , and not that I wouldn't understand 16y exams

    EDIT: So you are saying that inside the GPU there is an additional transformer? Well , that would make sense finally.
     
  17. ghost101

    ghost101 New Member

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    I think its all done via capacitors. But I know very little about this kind of stuff, so don't take my word for it.
     
    Last edited: Sep 24, 2009
  18. largon

    largon

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    Basic physics FTW.
    Yes, there's a voltage converter, or rather, several independent converters serving different loads on every video card, like on motherboards which have converters for CPU vcore, memory voltage, chipset voltage, bus voltage, etc. Video cards are no different - it's not like the GPU chip is running on raw 12V from the PSU. Ever heard people talk about "VRMs" - voltage regulation modules?
    As W1zzard, who is the developer of GPU-Z, stated in 1st reply of the thread, the current figure GPU-Z reports is not 12V current but the current the GPU draws from the video card's GPU VRMs.
    It seems you passed the exams, assuming you did, but did not actually understand the subject.
     
    Last edited: Sep 24, 2009
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  19. RuskiSnajper

    RuskiSnajper

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    Sorry guys , Now I get it:laugh:


    So that's VRM , been hearing a lot, but didn't know what it stood for.
     
  20. ghost101

    ghost101 New Member

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    Cheers. Never came to my mind they might be changing the voltages lol.

    http://en.wikipedia.org/wiki/Buck_converter

    I am glad I never thought of doing electronic engineering.
     

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