# VDDC Current ?

#### chaotic_uk

what does this mean ? , at full load it reads 46.5 A . is this the load it uses ? , if so my psu is not long for this world as it is only rated at 41A max for all 4 of my 12v rails

my psu is the 550w model

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#### chaotic_uk

no the reading is from the latest version of GPU-Z , in the pic below is at idle

#### W1zzard

Staff member
your psu can supply 41 A @ 12 V = 492W
the card is pulling 46.5A @ 1.5V (or how much it is, VGPU) = 69.75W

you are perfectly fine

#### chaotic_uk

your psu can supply 41 A @ 12 V = 492W
the card is pulling 46.5A @ 1.5V (or how much it is, VGPU) = 69.75W

you are perfectly fine
many thx , i was alittle worried lol

#### acrowley23

##### New Member
your psu can supply 41 A @ 12 V = 492W
the card is pulling 46.5A @ 1.5V (or how much it is, VGPU) = 69.75W

you are perfectly fine
So generally this Value is the cards power consumption ?
But it must be 46.5A x 1.263 Volt= 58,72W , isnt it ? vcore is 1.263 Volt ?

I have ~9A in Idle @ 200/200Mhz, so i have ~11W ...can it be correct?

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#### nafets

##### New Member
I'm making an assumption here that the VDDC current listed in Gpu-Z is only for the GPU core and it's circuitry.

You also need to include the MVDDC current and it's usage to factor in the total power consumption of the video card.

The HD4870 has been tested by Xbitlabs as using 65.2W during 2D IDLE as seen below:

My HD4870 running at 500/900 @ 1.263v (2D IDLE) reports a VDDC current of 25.7A, in Gpu-Z.

25.7A x 1.263v = 26.963W

65.2W - 26.963W = 38.237W

You can figure that the HD4870's MEMORY is consuming most of that remaining 38W.

This would be a great explanation (if true) as to why underclocking the MEMORY on the HD4870 saves so much regarding power consumption, while underclocking the GPU does very little...

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#### chaotic_uk

last night during gaming it reached 56.5A , so does this mean it uses the following ?

56.5 x 1.265 = 71.47 w

#### acrowley23

##### New Member
last night during gaming it reached 56.5A , so does this mean it uses the following ?

56.5 x 1.265 = 71.47 w
yes...this is how it works

My card reaches 9W in Idle @200/200Mhz and ~25 @ standard 500/900

Must take a look at my load Values tonight

#### chaotic_uk

so does this mean my card is not reaching full speed ? , i thought they used more power while gaming than that

#### nafets

##### New Member
last night during gaming it reached 56.5A , so does this mean it uses the following ?

56.5 x 1.265 = 71.47 w
As I said before, we're possibly missing a variable here. There's no way the HD4870 is only using a total of 72W during 3D Load, as I showed with the Xbitlabs results. It's more likely almost twice that amount...

#### chaotic_uk

i would agree with you on that , no way it uses that small amount of wattage seeing it needs 2x pci-e 6 pin power

#### W1zzard

Staff member
thats the gpu only afaik. there is also memory, vddc circuitry conversion inefficiency and other random components

#### chaotic_uk

so how much wattage does gddr5 use ?

#### WarEagleAU

##### Bird of Prey
you have a seasonic 550w PSU an S12 modular version. You are fine to go so I Wouldnt worry about it. Seasonic (who also makes Corsairs PSUs) are underrated for their wattage.

#### chaotic_uk

the s12 energy plus is not the modular version sadly , it has more wires than the national grid lol .

as for them being under rated , it is true and it makes my old ezcool 700w look very poor

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#### LuxZg

I'm making an assumption here that the VDDC current listed in Gpu-Z is only for the GPU core and it's circuitry.

You also need to include the MVDDC current and it's usage to factor in the total power consumption of the video card.

The HD4870 has been tested by Xbitlabs as using 65.2W during 2D IDLE as seen below:

My HD4870 running at 500/900 @ 1.263v (2D IDLE) reports a VDDC current of 25.7A, in Gpu-Z.

25.7A x 1.263v = 26.963W

65.2W - 26.963W = 38.237W

You can figure that the HD4870's MEMORY is consuming most of that remaining 38W.

This would be a great explanation (if true) as to why underclocking the MEMORY on the HD4870 saves so much regarding power consumption, while underclocking the GPU does very little...
Hehe, sounds more logical than my lousy assumptions that there is no PCIe power included in that, or that this is just for one 6-pin power connector or some other out-of-this-world stupidities
Your explanation sounds a bit more reasonable, as VRM sensors report 1.2625V x 25.7A, and we all know that memory is running on different voltages than GPU (if I remember it right it was ~1.5V).

EDIT: Oh, and tnx for the xbit picture, I was looking for it, but only found 4850.. dumb me, ofcourse it's in newer 260/280 review if there was no real 4870 review, dooh! EDIT2: I've made a little PDF with all recent Xbit's power measurments.. You can find it over here. Btw, note that they use 410W Chieftec PSU even for some extreme overclocking and all recent VGAs I'll go jump in Vista and will run the same 3D bench, so we'll hopefully know what amps we have on those 130W..

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#### H82LUZ73

yes...this is how it works

My card reaches 9W in Idle @200/200Mhz and ~25 @ standard 500/900

Must take a look at my load Values tonight
My load values are 38.4 or something.that is 2 4870`s also.Idle is 25.7

#### LuxZg

Well, measured in Vista 64bit SP1, on 4870 card, I get no more than 50.8A in GPU-Z.
There's a catch though, I couldn't bench on same settings as XBit, as my "wrong" monitor is hooked up to this PC, so I'm capped by my Syncmaster 793MB to 1280x1024 :/ I'll exchange it with the other Syncmaster (757DFX) as it can run at up to 1920x1440 @ 64Hz, and I'll re-bench it once more.. Just have to wait for my better half to stop playing on the second comp

#### H82LUZ73

Well, measured in Vista 64bit SP1, on 4870 card, I get no more than 50.8A in GPU-Z.
There's a catch though, I couldn't bench on same settings as XBit, as my "wrong" monitor is hooked up to this PC, so I'm capped by my Syncmaster 793MB to 1280x1024 :/ I'll exchange it with the other Syncmaster (757DFX) as it can run at up to 1920x1440 @ 64Hz, and I'll re-bench it once more.. Just have to wait for my better half to stop playing on the second comp
I just did the same thing ....Ran 3dMark06 and left Gpu-Z run in the background so i could see it between test`s,I finally have my cards within 2 degrees of each other.

#### LuxZg

Well, i've tested in 1600x1200 3dmark 06 just now, and it's same 50.8A, so we could say that's 50.8A is 130W by Xbit measurments.. But thing is that Crysis benchmark pushes it to 61,6A in DX9, so maybe even more in DX10 and/or 64bit. Will try .. again

Here it is.. Interesting things, interesting. i'll have to do more benches to confirm it, but VEEEERY interesting. Crysis on 1600x1200, very high, 64bit, dx10, so all maxed - 50.8A Same as 3dMark. But I was having 61.6A in WinXP/DX9, and I guess I've just found out why all my Crysis benches are 11-12fps lower in Vista than in XP. It works less, as amps clearly show.

But let's not get ahead of ourselves, I'll make me a table with results, and I'll bench one mroe time both in Vista and XP. Too bad that 3dmark ain't working in my XP install.. and too bad Vista locks me to 1600x1200 while I can do bothe 1600x1200 and 1680x1050 in XP. Dooh!
Lots of benches to do, see you people in a few hours

EDIT: Well, after a lot of benches I have one conclusion.. Don't believe in Crysis Benchmark Tool, as it has problems with setting the right resolution, a lot of times. I've ended up taking screenshot of every bench run, just to confirme I'm at right resolution
As for the max current, I'm still on 50,8A for 3dMark 06 with Xbit settings, and most I've pulled in new benches was 56,5A on 1600x1200, both in XP, Vista is always lower in consumption. Sorry, forgot to test 1680x1050 in XP, that gives me 65A peak :-O But not higher VRM or GPU temps compared to 1600x1200 (actually, completely same or 1C lower). Ok, I'm done with testing today, gonna go and play now a bit

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