[Cybiote]

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.

[frozenport]

Doesn't that only include radiated heat? If I touched it, it would be hotter.

[saagarjha]

It wouldn't be hotter (the temperature wouldn't change), but it would transfer more heat to you.