By: Ungo (a.delete@this.b.c.d.e), April 23, 2013 10:08 pm
Room: Moderated Discussions
David Kanter (dkanter.delete@this.realworldtech.com) on April 23, 2013 12:48 pm wrote:
> That's true, but remember that you're measuring Tj for the CPU+GPU. That's physically
> a separate die from the eDRAM. I doubt the eDRAM has anything that's quite so
> hot as an FPU inside, so I rather doubt that you'd see high Tj.
I'd expect the two die to be thermally coupled though. It's difficult for them not to be. There will be conduction through the package substrate's power and ground planes, and (more importantly) through the heat pipe connecting the two die to the HSF. So I wouldn't be surprised if the eDRAM die Tj tracks the CPU+GPU Tj despite the disparity in W/mm^2.
> That's true, but remember that you're measuring Tj for the CPU+GPU. That's physically
> a separate die from the eDRAM. I doubt the eDRAM has anything that's quite so
> hot as an FPU inside, so I rather doubt that you'd see high Tj.
I'd expect the two die to be thermally coupled though. It's difficult for them not to be. There will be conduction through the package substrate's power and ground planes, and (more importantly) through the heat pipe connecting the two die to the HSF. So I wouldn't be surprised if the eDRAM die Tj tracks the CPU+GPU Tj despite the disparity in W/mm^2.