i3 is just lower clocked i5/i7 without Turbo. It's not only HT, it offers much greater clock for clock performance when compared to C2Ds. How much is still a question but seeing that Nehalem/Westmere provided something like 20% over C2D and SB is supposed to be ~15% faster than Nehalem, it will be nice. Definitely the biggest bump in 13" MBP's CPU since the introduction of Intel CPUs.
As I said above, i5s cost more and in the end doesn't provide much to the average end user.
The only problem with the i3 processors is that the only two that currently fit with the MBA's thermals are the
i3-380UM (1.33Ghz) and the
i3-330UM (1.20Ghz). Not exactly barn-burners, especially w/o Turbo-Boosting.
All of the other i3 Chips are 35W TDP chips - so they won't work in a MBA. Now these are Arrandale chips, not Sandy Bridge, but I don't believe Sandy Bridge is gonna up the clock speed that drastically.
To me, an i3-UM processor is no better than the Core2Duo offerings they have in the 13" model right now.
At least the i7's have "LM" models that don't skimp on base clock-speed as much. Like the i7-660LM at 2.26Ghz up to 3.06Ghz on turbo. It's a 25W part, so it might be tight with the thermals in a MBA tho. But if they can pair this speed with Sandy Bridge's better graphics... that would be a KILLER MBA.
Again, all of the stuff I'm referencing if Arrandale chips - so not Sandy Bridge yet, but if they can pull all these clock speeds off with Arrandale, I expect Sandy Bridge to be slightly better, (with a much better graphics core).
In other news today: Engadget reports that someone got their hands on an
Unreleased Alienware Laptop with a Sandy Bridge chip in it (the i7-2630QM) and the integrated graphics chip scored a 15,940 on 3DMark06.
If this isn't a Hoax, and it doesn't seem like it is... and if the graphics chip in the i7-2630QM is clocked the same as the graphics chip in the i7/i5 destined for the MBP's... than the intergrated graphics chips of SB are AMAZING (and definitely *this* amazing when paired with an i7 CPU.
To put it in comparison... 3dMark06 scores for other Apple GPUs (links go to reference sites):
GMA950 -->
91
9400m -->
2,207
320M -->
5340
330M -->
6,746
That compares to a SB Integrated Chip score of 15,000! Wow. This seems much too good to be true...?
Look at these screenshots:
A 320M paired with a Core2Duo 2.4Ghz: 5340
A Sandy Bridge with IGP and an i7-2630QM: 15,940!