Why Ivy Bridge Is Still Quad-Core?

[CPUarchitect]

IVY will not increase IPC.

Even some people in forum.Beyond3D are arguing that Haswell do not need to put much attention in increasing IPC too. They said, cos of the idea of reducing powerconsumption, there should be only one AVX2 FP unit in Haswell.

Certainly not. It's all about performance / Watt, not power consumption itself. And you don't maximize performance / Watt by having only one AVX2 unit in a 4/3-wide architecture.

Having two AVX2 units won't mean Haswell isn't power efficient in absolute terms. Some Haswell parts will have a very low (idle) power consumption thanks to the mature 22 nm + Tri-Gate process, aggressive clock gating, modest clock frequencies, and only two cores. Note that there are already 17 Watt TDP Sandy Bridge parts so fitting Haswell within the 15 Watt bracket for ultrabooks shouldn't be overly hard. :whiste:

 

[Nemesis 1]

AVX2 features 256-bit vector instructions for integer operations, fused multiply-add floating-point instructions, and most importantly memory gather instructions. The latter allows to parallelize almost any code loop that has independent iterations, up to a factor eight.

I thought it was a factor of six. This must be updated material you got a link for that?

 

[CPUarchitect]

I thought it was a factor of six. This must be updated material you got a link for that?

AVX2 is 256-bit, and since most code uses 32-bit variables that's eight 32-bit lanes. Note in the link how gather, vector shift, and permute all have DWORD variants.

Of course in practice it will be hard to achieve an eightfold speedup, so a factor of six might be a more realistic best case, but either way it's a lot more promising than the 10-20% increases we've been seeing for the last few years!

 

[rgallant]

question

seems like there is a pci-e 2.0 to pci-e 3.0 switch chip on the sb-e mb for when the 3.0 gpu's are released.<<<<<< confusion sets in .

-so it seems pci-e slots with 2.0 gpu's won't run at 3.0 speeds ????
-thats ok for 2 cards what about 3 where 2 slots drop to x4

-so will the IB Z77 chipset run at full 3.0 speeds if say 2 x pci-e 2.0 gpu's cards and some other pic-e card is used ?
Z77 break down of slots
1 x16 or
2 x8 or
1 x8 + 2 x4 will they all run @ 3.0 speeds if 2 x 2.0 gpu's are used.+ other card
PCIe 3.0
-seems like a deal breaker if all pci-e slots do not run @ 3.0 speeds for all cards for multi 2.0 gpu's.
or maybe I,m missing something.
-edit to answer my own question no it won't , as the 3.0 spec's need all 3 - gpu, slot switch and cpu , bummer