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Comment by dr_zoidberg | Hacker News Reader

> Can the Broadwell use the 128MB EDRRAM from the iGPU as a L4 cache if the iGPU is not used? Would that actually make such a difference?

That's exactly what it does, and it gives you a "free"* ~20% increase in memory operations performance (which tends to be a ~20% increase in general performance).

* not actually free because you paid for those 128MB EDRRAM...

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Nice, now I'm wondering why Intel doesn't slap 128MB EDRAM on an Kaby Lake i7 4 core 8 thread and then release it for the enthusiast platform x99. Maybe even select chips to make it possible to release them at 5ghz. Of course with a large premium (expensive EDRAM etc.).

The Iris chip (the extra EDRAM for GPU/L4) is seen by Intel as a performance improvement for mobile solutions (ultrabooks, MS Surface Pro, maybe Macbooks some day?) and not a desktop solution.

But from a consumer point of view, it increases performance (either for graphics or for the whole system if I have a discrete GPU), and it can also help with GPU numerical processing, because you get "free" transfers from memory (L4) to graphics memory by flipping a bit (or a few bits) in hardware. Don't know why this wasn't expanded further, appart from the cost of the embedded RAM.

This is what I got frustrated with and decided to stop waiting & buy a Ryzen, in fact. I've been looking forward to an enthusiast segment desktop chip with eDRAM and Iris/Iris Pro (or better!) from Intel, for a few years now, but it hasn't surfaced.

Because they had no competition, so no desire for higher performance. They can easily remove the GPU from Kaby Lake, use that transistor/thermal budget for 4 additional cores and add 128MB of L4 cache for a monster CPU.

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