Not really understanding (and have tried Googling) why NV dies have this glassy effect, where Intel CPUs have the metal cover. Difference? Because? I reckon @edzieba is going to be the "font" and centre with this one, but other contributions welcome...!
That is the chip itself. It's silicon. It's exposed. On a CPU it has a IHS which covers it with copper to transfer the heat and protect the die.
No way! Never knew silicon had that finish, but suppose it makes sense now you say it. Why don't the GPU chips need a heat spreader then? I would have thought chips were fairly equal and therefore need similar treatment...?
I think it's mainly due to the fact that GPUs already have the heatsink fitted at production, while CPUs bought at retail require the HSF to be fitted, and there's more scope for clumsy hands to break or chip the silicon. The IHS on the CPU protects from this. There used to be CPUs with bare silicon like the Athlon XP, and they had some pads at each corner to try to protect against clumsy fitting.
Its in the name, Integrated Heat Spreader It stops the thermal density of the CPU from overwhemling heatsinks. Well, it does when they're not thermally bonded with awful TIM!
Now that's a trip down memory lane. Genuinely surprised that much younger me never buggered a chip up in that era of processors.
Protection is the main thing, thermal performance is very marginally decreased by the extra copper shim layer vs. direct bare die contact with the coldplate. Older dies were both smaller and thicker than current dies, making them more robust (though still snappable during HSF install, hence the hatred for the old AMD lever-it-down-with-a-flathead clamp mount). More recent dies are both much larger in area, and thinner in profile. CPU heatsink install is an expected end-user activity and arguably within warranty, whereas GPU heatsink replacement is not, so CPU packages need to be physically robust to avoid high wastage. Then there's die coverage: with modern large dies there are physically different bits that get hotter based on what specific CPU you have, or even what workload you are running! This ended up being a big gotcha with first gen Threadrippers overheating with most 3rd party coolers due to the dies being so far spaced out compared to anything else on the market that existing cooler coldplates physically couldn't cover them adequately. An IHS can't solve this completely, but it can mitigate it and allow for coolers that can be used across multiple different processor lines (and multiple different sockets) rather than being designed around a specific die layout. e.g. a Comet Lake die will have the CPU cores clustered in a strip in the middle of the coldplate, whereas a Ryzen 3 CPU has the CCX dies spread out to two of the corners. Weird or even asymmetric physical die layouts are also a good reason to have an IHS: to avoid a coldplate rocking about on a mounted CPU as it is being tightened down and snapping the corner of a die off.
