Decreasing 2D speeds and voltage on 4850

[IWasHungry]

While looking through my Catalyst Control Center profile .xml file (You can find it at Documents and Settings/"username"/Local Settings/ATI/ACE if you have CCC installed and a profile created), I found a set of values that control not just 3D clocks but 2D clocks also:

<Feature name="CoreClockTarget_0">
<Property name="Want_0" value="50000" />
<Property name="Want_1" value="50000" />
<Property name="Want_2" value="62500" />
</Feature>
<Feature name="MemoryClockTarget_0">
<Property name="Want_0" value="75000" />
<Property name="Want_1" value="75000" />
<Property name="Want_2" value="99300" />

For example, I can lower the 2D core clock from 50000 (500MHz) to 40000 (400MHz).
In the interest of lowering energy consumption, is there any drawback to lowering 2D clocks?

Also, it appears I can mess with the voltages as well:

<Feature name="CoreVoltageTarget_0">
<Property name="Want_0" value="1046" />
<Property name="Want_1" value="1046" />
<Property name="Want_2" value="1082" />
</Feature>
<Feature name="MemoryVoltageTarget_0">
<Property name="Want_0" value="0" />
<Property name="Want_1" value="0" />
<Property name="Want_2" value="0" />

Given the memory voltage values are all 0, I probably shouldn't mess with those (I have no idea why these values are 0s nor what numbers to put in here), but it looks like 2D and 3D core voltage can be modified. Anyone think this is a bad idea?

 

[vixro]

You can be the test pig. ;D

 

[Kuroimaho]

As I recall the voltage is 0 because in the BIOS voltage is preset by the manufacturer and the driver can only choose which level it loads, but been a while since I tinkered with ATI bios.

 

[IWasHungry]

The lowest I could set the GPU/RAM was 450/675. If I set the number any lower, nothing would happen. I measured power consumption with a Kill-A-Watt.
500/700: 222W
450/675: 219W

Also, I'm a bit scared to mess with GPU voltage. I replaced "1046" (1.046V?) with "1000" (1.000V?) to see what would happen, I didn't see any temperature or wattage difference.

 

[MadMan007]

The three lines appear to be 2D, low power 3D and high power 3D. Which 1046 did you change?

 

[IWasHungry]

The three lines appear to be 2D, low power 3D and high power 3D. Which 1046 did you change?

In this entire experiment, I change both Want_0 and Want_1 because I don't know which is regular 2D.

One thing I'd like to know is why ATI doesn't set their 2D clocks to something much lower (Like 100/150 or something). A 4850 at 1/6 its' normal power is still way more than enough for 2D graphics.

 

[MadMan007]

Oh. Maybe the BIOS settings for voltage override the ones in the CCC .xml? Or there are hard limits due to hardware which you can't go beyond. I think some people at XS experienced this with increasing voltage...