Disabling an Intel G45 Graphics Chip

[Jaguar]

My music/HT server uses a Supermicro board with the Intel G45 onboard graphics chip. This is a dual-boot system for the Audio and Theater sections.

For the audio section, I'd like to disable the onboard graphics and use the basic VGA driver in memory; thereby eliminating a voltage draw on the board and reducing jitter, in theory. However, I'm trying to avoid the extra step of re-enabling the G45 in the bios every time I switch to HT mode. My thought is to leave the G45 always enabled and disable the G45 driver in Win 7 audio section.

I'm not sure if the convenient solution is just as good as switching the bios? If I disable the chip only in the OS it's not working to process data. However, I don't know if disabling in the bios would bypass the chip entirely or put it into some sort of hibernation state.

Maybe there's some EEs out there who can shed some light on how these chips work with the bios, in this sort of situation.

 

[mep]

I don't see how a voltage draw from the G45 chip is going to induce jitter on the audio. You might be overthinking this. Try changing the bios to turn it off and see if you hear any difference before you go crazy thinking about which solution for turning it off is the better or easier one.

 

[amirm]

There is only one graphics subsystem. So even when you use the VGA mode, the graphics subsystem is alive. To disable the on-board video means not getting any video at all. That feature is there so that you can use an external graphics card.

Have you actually disabled it and it still boots in VGA mode? If so, you have me stomped .

 

[Jaguar]

Hi Amir, I'm working from the plans on the CMP2 website. The author recommends disabling the onboard graphics and running the video in VGA mode in the CPU. I don't know how much this could reduce jitter or whether I could hear it in my system, but this guy claims to have measured the jitter in his system at 50ps, which if true is pretty impressive. Assuming I can get this to work in my system, I'm trying to figure out whether there's any drawback (at least in theory) to not disabling the chip in the bios.

http://www.cicsmemoryplayer.com/index.php?n=CMP.07Optimisations

 

[Jaguar]

I was mistaken about the BIOS having an adjustment for the graphics chip, it's for the HD audio chip. However, I have done some experimenting. You can disable the HD graphics chip in the Device Manager and the VGA driver will kick in. To my surprise I didn't need the VGA cable I purchased, because the HDMI was able to carry the VGA signal.

Of course, nobody would do this unless they wanted to try to decrease jitter, at the expense of the graphics. It's a big sacrifice, as they're not pretty.


Update: another quick correction to clarify how this works. I am told that disabling the graphics driver does not disable the GPU it just reverts to using the generic VGA driver on the GPU. This is different than what I read earlier about the graphics running on the CPU, but I think this explanation is probably correct.