Does disabling on-board graphics save power?

MoJo · Post by **MoJo** » Sat Aug 11, 2007 7:36 am

It may seem obvious, but does disabling on-board graphics really save any power?

I am looking to build a HTPC with Radeon HD 2400 graphics card. I could buy a mobo with 2 RAM slots and VIA Unichrome graphics, or 4 slots and on-board GeForce 6200. Since the price difference is less than Â£1, I would prefer the latter, but reading reviews it seems the NB gets rather warm.

Assuming the on-board graphics are disabled, does that part of the chip actually power down? Or does it just sit there, using power but not doing anything? I can't seem to find any reliable info on the topic.

tehfire · Post by **tehfire** » Sat Aug 11, 2007 1:30 pm

I think the chip just powers down, though I don't have any proof.

So your first system would be a VIA chipset and an AMD GPU, and the other system would be one with a GeForce 6200 integrated into the MB? Of those two, the latter would be more efficient, as integrated is almost always less power-hungry than discrete.

Not sure about the quality of onboard, however...

MoJo · Post by **MoJo** » Sat Aug 11, 2007 2:12 pm

Ah, sorry, I think my initial post was misleading.

I am going to use the Radeon HD 2400 Pro in both systems. The reason being that it has hardware decoding of H.264 and VP-1 (WMV) video, so will be fully capable of playing back HD downloads/HDDVD/BluRay etc. The only reason I am upgrading from an XBOX Media Centre is that it cannot handle H.264 even at SD, and more and more stuff is going that way now.

I have a Via C7 board. Disabling on-board graphics does not seem to make any difference to temperatures, so presumably either the VGA is so low power it doesn't get hot or it's not powered down, just logically disabled by the BIOS.

vortex222 · Post by **vortex222** » Tue Aug 21, 2007 11:10 pm

I don't think it saves that much. although its not fully active it is not in any form of 'shutdown' or low power state like a cpu would go into. I still think it consumes the amount of power any powered but inactive chip would. The northbridge would need separate power planes to fully shut it off.

Silicon still has a certain amount of leakage rather the transistors are open (in use) or not.

MoJo · Post by **MoJo** » Wed Aug 22, 2007 5:36 am

Thanks vortex.

As a side note, The AGP version of the 2600 is rubbish, and AVIVO does not work with it. The only reliable way to play back 1080i H.264 video is to have a fast CPU.

Drexl · Post by **Drexl** » Wed Aug 22, 2007 4:28 pm

Are those your only two choices in boards? You couldn't get one with no onboard video?

jackylman · Post by **jackylman** » Thu Aug 23, 2007 5:20 pm

I think you should take a look at this article and reconsider your choice of video card. (i.e. move to the 2600 or 8600 series)

MoJo · Post by **MoJo** » Thu Aug 23, 2007 8:34 pm

Drexl: all the cheap mobos these days have on-board video, basically you have to look for discounted boards to find one without. I suppose they are all aimed at the basic low-cost office market.

jackylman: I did actually try the 2600 (maybe you read 2900?) and while I'm sure it works well enough on PCI-e, the AGP version is rubbish.

I wanted to get an AGP card so I could re-use an old Duron 1.2 based machine. A low end CPU will also be easier to cool quietly. Since it didn't work I will just have to buy a PCI-e board and CPU to run the PCI-e 2600, in which case I might just as well get a low end X2 CPU and rely on software decoding. Even a 3800 X2 can decode 1080i/p H.264 with CoreAVC.

It's a shame most cheap mobos only have VGA and not DVI, although for some reason most cheap monitors have only VGA as well. You would think a DVI port would actually be cheaper, seeing as a VGA port has to include analogue to digital conversion hardware as well.