Nice Upgrade for OEM notebooks!
This CPU was purchased to upgrade the i5-480M is a MSI notebook purchased by me new in 2011. While ran great when new, over time, with all of the Windows Updates & installed software, would freeze at boot if opening a browser.
Got tired of this, and after a year of searching, and finally the price dropped to what I was willing to pay, pulled the trigger on the i7-620M after carefully again reading reviews, on eBay & in articles. While the GHz level is no higher than the i5-480M, and the cores were the same, this CPU features a 4MB cache rather than the 3MB one I had, and no there's no more freezing.
Just keep in mind to get some quality thermal paste (I use & recommend Arctic MX-4), which can be found in a 4 gram tube on promo, likely here on eBay. Like I did with this CPU, just check seller feedback, it's not everything, but a lot, as those with higher feedback ratings wants to keep it that way. And be sure to clean the heatsink up really good, if there's a fan that can't be removed, carry outdoors & using a can of compressed air, blow the fins out really good, and clean the place(s) where the thermal paste with 91% alcohol.
Be sure not to over apply the paste, less is more, and this can be checked after wiggling the heatsink a bit before booting. If too much, remove any excess that squeezes out with a razor blade of similar object (don't smear it), and do the same with the edges of the heatsink where that also overspread, this is a good place to remove a bit, By checking before boot, can save from having to do all over again.
The i7-620M is a fantastic CPU that'll last a long time if purchased from a reputable seller, and uses no more wattage than the i5 & i3 models of the same generation (Arrandale series). In most cases, should produce less heat, because not taxed to death with running software. Plows through work that the others doesn't, and the 4MB cache give it an extra burst of speed.
Be sure to download the Intel 2.6 Turbo Technology Monitor from Techspot after install, that'll show one in real time the clock speeds. If I could rate this CPU on a 1-10 scale, would give it 10. I'm not knocking off anything for not being a quad core, because it's not advertised as such. Plus on notebooks, even if a quad could physically fit, an upgraded PSU would be needed, plus one has to consider the heat factor, a notebook built for a dual core CPU had bast stay as such.
Good Luck with the upgrade!