Power consumption problem

[JaRoD]

I just "upgraded" from an atx to a matx motherboard but it uses about 20w more now at idle

The atx one is a abit ib9 with p965 chipset and the new matx is an asus p5kpl-am that uses g31 so just going by the tdp of the chipsets the asus should use a few w less so not really that much of a difference. I measure powerconsumption with an apc ups that I'm guessing is farily accurate even if it seems to only measure in 3w increments. Before usage was 90-95w idle but now it's about 115w.

However I did some testing and removed everything extra like graphics card, hdds, dvd, soundcard and everything extra in bios is disabled. Now power usage is about 36w Well long story short, I think the integrated grahics card isn't really turned off when it's disabled. Could it be so? And it also seems like my ati 4850 uses about 50w idle and that's when it's downclocked to 300/500 which is the lowest possible without crashing weirdly enough

I've heard that a downclocked 4870 actually uses less power than the 4850 when downclocked, anyone have any experience with that? and by extension I assume the same might be true of the ati 4890 card.

And this bios is totally unable to undervolt... but it can overvolt pretty well. I got this motherboard and an antec p180 mini since I got both very cheap.

Any advice is welcome and thx in advance for any help

ps. please ignore any eventual bad spelling since I watched tv while typing this

[jessekopelman]

Well long story short, I think the integrated grahics card isn't really turned off when it's disabled. Could it be so?

I could be, but the GMA3100 IGP it has isn't going to use more than 3W when it is idle and if you have a discrete card installed, it will certainly be idle. So, this is not the culprit for your 20W discrepancy.

Your post confuses me. Are you saying that the only thing you changed was the MB? Everything else stayed exactly the same and yet your power consumption went up 20W? If that is the case, my first guess is that you had Speedstep (EIST) enabled on your previous motherboard but you didn't enable it through the BIOS of your current one.

[yuu]

It probalby has something to do with low vrm efficiency partially, there are 3 vrm phases, each one of them having 2 mosfets, compared to the traditional 3 mosfet design,

and also g31 runs hotter than the 965.

some asus boards are reported to be more power hungry than competitive products from other companies, so there are more idle issues out there than just the poor vrm desigh.

integrated graphics is never really turned off, 965, p35 and p45 have it, it is there.

4850 4870 4890 have the worst idle among all cards, focus on future 40nm products and hope that they fixed the 50-60W idle issue on today's cards.

[JaRoD]

I changed the motherboard and the case. The p180 mini does have a 200mm fan but I haven't actually checked how much that uses but can't imagine it would be that much more than a regular fan.

I'm have to go check the bios, but I'm pretty sure I did enable speedstep in bios but it does seem like the cpu speed is at full even at idle.

//edit

Checked the bios and speedstep was indeed enabled but c1e wasn't, but now with it enabled idle consumption did go down about 10w. And the last 10w is apparently then down to the inefficient board. Hopefully the 40nm generation ati cards will be better at idling and will be out soon (and be faster )

[quest_for_silence]

I just "upgraded" from an atx to a matx motherboard but it uses about 20w more now at idle

It seems that µATX boards tend to be less efficient than ATX ones: you may refer to DFI LP Jr 790GX SPCR's review and subsequent forum discussion for some more hints.

Regards,
Luca