News for hackers. Stuff that matters.

A comment on The Dark Silicon Problem and What It Means for CPU Designers (2013). Parent comment

Re:The Dark Silicon Problem and What It Means for CPU Design... by andlier on Sunday July 22, 2018 @02:58PM (#17588230)
After a quick napkin calculation+google it seems the sun has around 20kW of power per square centimeter. So not entirely unfeasible that a cooler star, or a nuclear reactor is closer to the typical 10-100W/cm2 of a modern cpu/gpu. Still some orders of magnitude off from our closest star. (Hope calculation is correct)
[ Parent | on HN ]
Re:The Dark Silicon Problem and What It Means for CPU Design... by perl4ever on Sunday July 22, 2018 @04:50PM (#17588850)
Looking at the wikipedia page on red dwarf stars[1], it appears a small star (M9V) might have 8% of the sun's radius and 0.015% of its luminosity. Thus, it would have about 156 times less area, and 2.3% of the output per area of the sun. So taking your figure as given, that means it would be less than 500W / cm^2.

[1]https://en.wikipedia.org/wiki/Red_dwarf

[ Parent | on HN ]
Re:The Dark Silicon Problem and What It Means for CPU Design... by Cybiote on Sunday July 22, 2018 @07:32PM (#17589464)
The temperature of the sun at its surface is ~5772 Kelvin. To get power per unit area, use Stefan-Boltzman: σ * T^4, σ * (5772 K)^4 ≈ 6294 W/cm^2. Dividing the sun's luminosity (power) by its surface area will also give a similar value.

A 815 mm^2, 250 W GPU will be 250 W / 8.15 cm^2 ≈ 31 W / cm^2.

[ Parent | on HN ]
Re:The Dark Silicon Problem and What It Means for CPU Design... by frozenport on Sunday July 22, 2018 @07:41PM (#17589498)
Doesn't that only include radiated heat? If I touched it, it would be hotter.
[ Parent | on HN ]
Re:The Dark Silicon Problem and What It Means for CPU Design... by saagarjha on Sunday July 22, 2018 @08:34PM (#17589679)
It wouldn't be hotter (the temperature wouldn't change), but it would transfer more heat to you.
[ Parent | on HN ]
Re:The Dark Silicon Problem and What It Means for CPU Design... by ars on Sunday July 22, 2018 @07:08PM (#17589380)
> 20kW of power per square centimeter

I'm getting 6300 W/cm^2 (see: https://news.ycombinator.com/item?id=17589371)

[ Parent | on HN ]