Undervolting IGP HD4200 worth the trouble?

autobulb · Post by **autobulb** » Thu Jan 07, 2010 9:06 am

Greetings, I have a recently purchased budget system based on the 785G chipset and the Athlon II X2 240. I have successfully undervolted the CPU to 1.175 and it seems to be stable while drawing 31W idle. That's not so bad but I was wondering if I could shed some watts by undervolting the onboard GPU. The problem is that although my motherboard allows changing the voltage of the GPU and sideport memory, it doesn't indicate what the default voltages are.

Does anyone know? I can't seem to find any answers online or through software.

Some side questions as well. GPU-Z says that the bus width of the 4200 is 32bit. That seems insanely low, isn't it at least 64bit? And finally, my sideport memory is only DDR2 while my system RAM is DDR3. Would I see performance gains from disabling the sideport memory and using only system RAM?

Thanks for your help!

Ksanderash · Post by **Ksanderash** » Fri Jan 08, 2010 4:47 pm

autobulb wrote:The problem is that although my motherboard allows changing the voltage of the GPU and sideport memory, it doesn't indicate what the default voltages are.

You can measure any V you like manually by the means of a digital multimeter. Just make us a few hi-res photos.

GPU-Z says that the bus width of the 4200 is 32bit. That seems insanely low, isn't it at least 64bit?

Yeah, 32bit width, and the RAM bandwidth isn't the crucial factor here, but the GPU weakness.

And finally, my sideport memory is only DDR2 while my system RAM is DDR3. Would I see performance gains from disabling the sideport memory and using only system RAM?

I think sideport is quicker. Just because the fact that manufacturer put in an additional chip (it costs much for him cause they count by millions). But you can check this sure by the benchmark.

autobulb · Post by **autobulb** » Sat Jan 09, 2010 2:51 am

Thanks for the reply. Unfortunately I don't have a multimeter (or the knowledge on its use) but I suppose I will try the different voltage options I have in BIOS and see if I can drop power usage while retaining stability. If anyone is interested I'll post the results.

Klusu · Post by **Klusu** » Sat Jan 09, 2010 5:45 am

Default is 1.1V (probably the lowest setting). The same for the memory: default is probably the lowest. The memory chip is rated 1.8V, I guess. 1.175 is not low. Low is 0.8 (I mean - idle). But 31W is excellent.
"manufacturer put in an additional chip " - and charged some 5-10$ more. The chip costs much less. I wonder why some do not put it in.