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| Power consumption in multi monitor desktop mode goes up 2.5x http://www.wsgf.org/phpBB3/viewtopic.php?f=66&t=18164 |
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| Author: | ChainSOV [ 16 Oct 2009, 15:55 ] |
| Post subject: | Power consumption in multi monitor desktop mode goes up 2.5x |
Thats what the german site ht4u.net found out. I wasn't aware of it and thought you might find it interesting too. Apparently the card clocks the ram and the chip higher and gives them more power if you plug a 2nd screen in. Power Consumption goes up 2.5x fold 21 -> 52Watts As does Noise 12dB (0,69 sone) -> 23 dB (1,76 sone) They say AMD answered them that in two-screen mode clocking GDDR5 the same as in singlescreen can lead to screen flickering. They didnt explain why the chip itself also gets clocked higher. JFYI, so you dont blindly assume the card is as silent and low consumptive in multimonitor desktop mode as its stated in all the single screen reviews. 52Watts is still pretty good compared to the competition ;) |
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| Author: | JKeefe [ 16 Oct 2009, 16:00 ] |
| Post subject: | Re: Power consumption in multi monitor desktop mode goes up |
12dB (0,69 sone) -> 23 dB (1,76 sone)I don't know at what distance those measurements are taken, but in any event either of those levels should be inaudible in the presence of any other computer noise. |
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| Author: | Dave Baumann [ 16 Oct 2009, 16:15 ] |
| Post subject: | Re: Power consumption in multi monitor desktop mode goes up |
They say AMD answered them that in two-screen mode clocking GDDR5 the same as in singlescreen can lead to screen flickering. Thats not quite correct - its not GDDR5 specific and has actually always been this way under the "activity based" PowerPlay mechanism. The issue is that to downclock memory you need to time the change within a panel VBLANK. With multiple monitors you can have ever so slightly different timings, so one panel will see a flash when the memory speed changes - even matched panels using different inputs (DVI on one, DP on another, for isntance) may have different timings in the EDID for the different inputs. The MCLK is kept high so that this doesn't become an issue. They didnt explain why the chip itself also gets clocked higher/ Engine clock is also directly related to the number of pixels being pushed out, which constantly needs to happen even when just refreshing a panel. In a the multi-monitor state I have to ensure that we are supplying enough pixel bandwidth to be refreshing the maximum panels supported x3. Note - irrespective of this, pure adding more panels in any scenario will increase the power because you refreshing those requires more memory bandwidth, pixel bandwidth, additional display pipes, additional board resources, etc. Power will always increase adding more panels. |
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| Author: | ChainSOV [ 16 Oct 2009, 16:38 ] |
| Post subject: | Re: Power consumption in multi monitor desktop mode goes up |
[quote]12dB (0,69 sone) -> 23 dB (1,76 sone)I don't know at what distance those measurements are taken, but in any event either of those levels should be inaudible in the presence of any other computer noise. The distance they measure at is 1 meter. In a silence optimized PC in idle this difference would be audible. sone is a linear unit for measuring loudness, so you can say it will be 2.5x as loud. And while <1 sone can be considered very silent, 1-4 sone is how loud normal talking sounds like from 1m distance. @Dave : thanks for clarification |
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| Author: | JKeefe [ 16 Oct 2009, 17:29 ] |
| Post subject: | Power consumption in multi monitor desktop mode goes up 2.5x |
I wasn't expecting 1m; that is a much larger distance that these measurements are usally taken at. Fair enough - with an otherwise silent PC this difference will take the card from being inaudible to audible. But really, what high-end graphics card doesn't make at least a little noise in an otherwise silent environment? |
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| Author: | Deke [ 17 Oct 2009, 00:02 ] |
| Post subject: | Power consumption in multi monitor desktop mode goes up 2.5x |
You can expect at least 10C jump in temp as well when using eyefinity when the Fan control is on automatic, now for some reason the auto fan control IMO lets the GPU get to hot, so before I get into a game I always turn the fan control back to manual and crank it upto 50%, it may be alittle louder but at least my GPU will not go over 65C on full load. For some reason the auto fan control only seems to know 21% and 24%? Deke |
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| Author: | Dave Baumann [ 17 Oct 2009, 02:24 ] |
| Post subject: | Power consumption in multi monitor desktop mode goes up 2.5x |
Bear in mind that the ASIC heat is not a direct correlation to the heat radiated into and out of the case - the amount of heat the graphics card gives off is a function of the power it is drawing. Although people pay a lot of attention to the reported ASIC temp, its a bit of a red herring. Generally speaking the fan tables are tuned for low noise. |
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