1 - Yes, some truth. It is generally believed that an i7 at 3.8ghz is the most usable CPU power available, and above that is extra heat and lost efficiency that does not corrolate to a reasonable amount of performance. 4.0 is better than 3.8, but by such a small margin that 3.8 is the smarter speed, longevity wise.
2. CM hyper 212+ and Sunbeam CCF are two coolers for a very low price (usually about $30) that should have no problem keeping an i7 cool at those speeds.
3. I don't own an i7, but from what I have gleaned, having a max of about 65c under load seems to be a reasonable target for those wishing for extra speed without killing their chip prematurely. An actual i7 owner/overclocker could clarify this if I am innaccurate.
1- Yourself say the target, if you can OC your processor at 4.2GHz stable with good temps, your target could be try to get a little more.
2- For price/performance, the Hyper 212+ is a very good option, but if the money isn't too important for your, go for the Thermalright Venomous that is excellent.
3- The safe temp for the i7-930 is around 80C.
Second, do some research on the cooler before you buy one. A budget cooler and an OCed i7 do NOT go together. If you are serious about OCing (even to 3.8 Ghz) you WILL need a decent cooler to handle heat output. When I bought my i7 860 on launch day, the only cooler I could get was the 212+ and I replaced it within two weeks when better coolers became available, it just didn't cut it with the heat and OCing.
Right now, a decent cooler would be a Megahalems, NH-D14 or as stated by Saint the Venomous X.
For longevity purposes I would stick to Intel's recommended thermal threshold and voltages.
@RJR, thanks for that - it was an interesting read.
@Everyone - A lot of people I've talked to are suggesting the Hyper 212+, a lot are suggesting Noctua/Megahalems/TRUE/Vanomous X. From what I could find, the best cooler out the box is the NH-D14 - only thing is, this thing is beast. I've googled around but couldn't find an answer - does anybody know if it will fit in my rig?
HAF 932, Asus P6X58D, Corsair Dominator and Sapphire Vapor-X 5870. By searching I already know that I'll have to mount it vertically, I just dont know if it will hit anything on my board while vertical.