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 Post subject: Radeon 7770 idle voltage with >1 monitor
PostPosted: Thu Mar 15, 2012 9:02 am 
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I notice that there's a thread about the same issue with nVidia cards below, but maybe it's still worth posting this, since AMD cards behave slightly differently...

I recently purchased an XFX Radeon HD 7770 (nice quiet card, btw), since it seemed to offer excellent performance per watt. And indeed it does when under load, but it is not quite so good at idle. The problem is that if I have my second monitor connected, then it stays at the maximum core voltage at all times. Specifically, it looks like this with two monitors enabled:

3D
Core clock: 1120MHz
Core voltage: 1.2V
Mem clock: 1300MHz

Idle
Core clock: 400MHz
Core voltage 1.2V
Mem clock 1300MHz

I understand why the memory clock can't be altered, but why not reduce the core clock more, and reduce core voltage? My old 4770 managed to do it ok. It's a substantial difference in power too; disabling my second monitor reduces my PC's idle power consumption from ~75W to ~65W, which is a lot for a card that's supposed to idle at about 3W.

Unfortunately neither GPU-Z nor ATI WinFlash can extract this card's BIOS, so I can't edit it in RBE, or even see what the default settings are supposed to be.

MSI AfterBurner won't let me reduce the core clock below 560MHz, and it won't let me set core voltage directly at all. I can indirectly reduce the core clock to 300MHz and core voltage to 0.95V by reducing the memory clock to minimum (not sure why altering the memory clock alone causes everything else to change, but it does), but of course I then get flickering when the memory switches speeds.

I also tried setting both monitors to the same resolution and refresh rate, which I have seen suggested as a possible fix in many places, but it makes no difference.

I'm pretty sure there's nothing I can do without the ability to edit the BIOS, but I felt like ranting here anyway. :x

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 Post subject: Re: Radeon 7770 idle voltage with >1 monitor
PostPosted: Thu Mar 15, 2012 10:07 am 
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Techpowerup and ht4u have been showing multi-monitor power use in their reviews. There's some progress with the new gen...just not a lot.

If you have an IGP based board, can you plug one of the monitors into it?

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 Post subject: Re: Radeon 7770 idle voltage with >1 monitor
PostPosted: Sun Mar 18, 2012 9:15 am 
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Joined: Fri Jan 20, 2006 10:12 am
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Location: UK
More weirdness... I noticed flickering when watching a Youtube video, so I checked GPU-Z, and it was switching to the following:

Core clock: 400MHz
Core voltage 0.95V
Mem clock 1125MHz

That's right, it actually reduces the memory clock when it is doing video decoding. Clearly either AMD or XFX have messed something up.

CA_Steve wrote:
...If you have an IGP based board, can you plug one of the monitors into it?

Good idea. I happen to have an IGP, so I enabled it and tried connecting the second monitor to it. Power consumption at idle went down to 65W. In other words, the IGP uses basically 0 power at idle (or at least it uses no more when enabled than when disabled). Surprisingly, it also copes fine with a 3D window spanning both monitors, albeit at a higher power consumption than with the 7770 alone driving both monitors.

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 Post subject: Re: Radeon 7770 idle voltage with >1 monitor
PostPosted: Sun Mar 18, 2012 3:41 pm 
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there ya go.

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 Post subject: Re: Radeon 7770 idle voltage with >1 monitor
PostPosted: Sat Jun 02, 2012 3:00 am 
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Location: UK
I saw it mentioned in various other places on the internet that the synchronization problem doesn't exist for DisplayPort, and thus using two monitors connected by DisplayPort would let the graphics card downclock normally. So, when I recently bought a new pair of monitors, I made sure to get ones with DisplayPort (HP ZR2740w), and... it doesn't work. There is no flickering with these monitors, so clearly there is no problem with changing the memory clock, but the idle clocks and power consumption are still just as high as before.

This is disappointing, as I'm not always going to have a motherboard with an IGP.

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 Post subject: Re: Radeon 7770 idle voltage with >1 monitor
PostPosted: Mon Jun 11, 2012 3:19 am 
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Joined: Fri Dec 19, 2008 2:55 am
Posts: 257
Location: Naples, Italy
Mr Evil wrote:
I notice that there's a thread about the same issue with nVidia cards below, but maybe it's still worth posting this, since AMD cards behave slightly differently...

I recently purchased an XFX Radeon HD 7770 (nice quiet card, btw), since it seemed to offer excellent performance per watt. And indeed it does when under load, but it is not quite so good at idle. The problem is that if I have my second monitor connected, then it stays at the maximum core voltage at all times. Specifically, it looks like this with two monitors enabled:

3D
Core clock: 1120MHz
Core voltage: 1.2V
Mem clock: 1300MHz

Idle
Core clock: 400MHz
Core voltage 1.2V
Mem clock 1300MHz

I understand why the memory clock can't be altered, but why not reduce the core clock more, and reduce core voltage? My old 4770 managed to do it ok. It's a substantial difference in power too; disabling my second monitor reduces my PC's idle power consumption from ~75W to ~65W, which is a lot for a card that's supposed to idle at about 3W.
[CUT]


Here comes ATI Tray Tools. Did you check if 7750 is already supported? It also allows dinamyc ddr5 frequency switching without any flicker (tested with a 5670 forced at 150/600@idle).

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 Post subject: Re: Radeon 7770 idle voltage with >1 monitor
PostPosted: Mon Jun 11, 2012 8:57 am 
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Joined: Fri Jan 20, 2006 10:12 am
Posts: 545
Location: UK
flapane wrote:
Here comes ATI Tray Tools. Did you check if 7750 is already supported? It also allows dinamyc ddr5 frequency switching without any flicker (tested with a 5670 forced at 150/600@idle).

Alas,
slickric21 wrote:
Ray Adams doesnt have a 7xxx series card, and looks like he wont be receiving one.
Plus he appears to be busy with other projects/real life.

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