1. There is no need for 1.50 volts. This was assumed by many pundits reviewing prerelease specs on SB before it's release and though corrected, the rumor just won't go away. Yes the published voltage was 1.575 but that was true for Nehalem/Westmere and you didn't see anyone warning about this with those systems. A THG pointed out the "designed for SB" modules are the same as the "designed for Nehalem/Westmere" modules, only thing that changed was the labels.
Sandy Bridge does not demand only 1.5v modules, it will be perfectly happy with 1.65v modules too. If someone tries to tell you that you must have 1.5v modules, then they are either trying to sell them to you, or they have been reading misinformation, or both! Another point to consider here, is that in your BIOS, if you head to the memory voltage setting, and enter 1.5v, the text will remain white/grey, if you enter 1.65v, it will turn yellow, and it isn't until 1.73v that it turns red, so at the moment, I'd rest assured that 1.65v modules are OK to use, and I have had this confirmed by Asus, Gigabyte and Corsair so far, as soon as I hear from anyone else, I will update this again.
We started getting email announcements of a new generation of LGA 1155-compatible RAM right around the same time as details of Intel's second-gen Core processors surfaced. The funny thing was that Intel’s memory requirements didn't change from Nehalem/Westmere to Sandy Bridge. The former platform’s documented maximum 1.575 V limit remains, with the same wink-and-a-nod from engineers that up to 1.65 V is safe.
The hardware itself didn’t change; just the labels (both internal and external.
THG's SB Memory test article tested 8 different sets of modules for SB. Only 2 (25%) were 1.50 volt
2. DDR3-1600 is easy .... higher than that, you start to pay a significant premium in both cost and "fiddling time".
3. CAS Latency is the last "spec" decision. As a "rule of thumb", I put CAS 9 in systems under $1200 and CAS 7 in systems over $1500 ..... in between it's a tossup depending on what owner wants. If playing w/ big spreadsheets and databases, CAD, rendering, video editing, photo retouching, CAS 7 is an automatic. In gaming, memory is only going to be a factor if the bottleneck isn't somewhere else. Where you will see the greatest impact of lower latency is diminishment of those annoying intervals in games where the minimum frame rate drops to annoying levels:
22.3 % (SLI) increase in minimum frame rates w/ C6 instead of C8 in Far Cry 2
18% (single card) / 5% (SLI) increase in minimum frame rated w/ C6 instead of C8 in Dawn of war
15% (single card) / 5% (SLI) increase in minimum frame rated w/ C6 instead of C8 in World in Conflict
4. Those cool looking heat sinks are exactly that cool "looking". The high profile fins can oft result in headaches from interference with CPU coolers. A remnant from "back in the day" when heat sinks actually performed a necessary function, reviewers including THG have reported that thermal performance can sometimes actually improve with their removal. Stick w/ low profile modules to take the interference concern off the table.