So HT would be useless for gaming and normal applications, while the better performance per core on the IB would be more noticeable in those situations.
Are the 2MB of cache on the i7 also negligible?
In an overclocked situation wouldn't the SB's better overclocking make up for the IB's better performance per core while retaining the HT?
1. HT is not helpful for most games. Many "normal" applications benefit from HT now however, so I would not be so quick to call it useless. For instance, 7-zip sees a tangible improvement with HT.
2. IB has slightly better IPC. Nothing earth-shattering, but in a benchmark like iTunes MP3 conversion, at an identical 4.5GHz clock IB gets things done 3seconds faster than Sandy Bridge. From this month's $2000 SBM machine:
3. Overclocking is a hit and miss. Some SB chips overclock high enough that it cancels out the IPC deficit. Some others won't make it that far.
The 2700k overclocks better than the 2600k.
5ghz is said to be easily achieved with the 2700k.
If you want high OCs & want a high performing CPU, for gaming & otherwise, 2700k should be your choice.
If its just gaming & some lightly multithreaded work, then the i5 3570k.