Intel Haswell with eDRAM cache gets pictured

VR Zone took a picture of an Intel Haswell multi-chip module that features onboard eDRAM cache memory to improve graphics performance. This memory will be used by Haswell CPUs with GT3e graphics, these parts will only come in BGA packaging and will be 55W quad-core parts for "performance notebooks". This 55W multi-chip package is designed to undermine discrete graphics cards offerings from NVIDIA and AMD under the 20W TDP envelope. The TDP of these 55W Haswell parts is pretty high for laptops, but they will have power management features to reduce net power draw. Further details can be read at TPU.

The graphics-enhanced Core "Haswell" processor is an MCM (multi-chip module) of two dies, the larger one is the actual "Haswell" processor complex with cores, uncore, and the larger GT3 integrated graphics core. While the standard Haswell silicon with GT1 and GT2 integrated GPU options, physically features up to 20 execution units (EUs), the large GT3 silicon features double that, at 40 EUs.

The first slide below details the Haswell GT3 package, while the second one details a standard Core "Haswell" implementation. You'll notice that apart from a larger graphics core, the processor features an additional stop on its ring-bus, the eDRAM PHY, interfacing with an external eDRAM silicon (the smaller chip on the MCM). Treated as L4 cache, the eDRAM chip provides higher bandwidth and lower latency than the main memory, for the graphics core to temporarily hold whatever it's working on, without clogging the main memory bus much. This is similar in principle to AMD's Sideport Memory, use of small amounts of faster memory on the motherboard to boost integrated graphics performance.