After ram upgrade, continuous beeps, but then boots ok?

May be that the RAM modules are not properly seated and the edge connectors need to be cleaned. It can also result from buying RAM not having the correct specs for your model. It can be caused by your machine not quite "liking" Corsair memory.

I would be inclined to buy a different brand of RAM such as Crucial.

Although I agree that it's odd that it will eventually boot, I'd still suspect the RAM - have you run the Apple hardware test? I don't know anything about the compatibility of Corsair RAM although I've seen several posts here detailing problems; personally, I would only buy RAM from a reputable vendor who tests the RAM with Macs and guarantees it to work as Macs are quite finicky about their RAM. The two most recommended here are OWC (macsales.com) and Crucial.

Exchange it and buy this -> http://www.crucial.com/uk/store/mpartspecs.aspx?mtbpoid=1C64A8C3A5CA7304.

I've had Corsair before and had no problems with it (just don't buy their "Corsair Value" labelled RAM) but when I decided to go for 16GB, I used Crucial and I've never had a problem. You might want to go to the Crucial site and use their System Scanner tab and small app to find exactly the kind of RAM that you need.

Good luck,

Clinton

So-called value RAM like Corsairs value line or Kingstons value line are often problematic in Apple machines. Apple tends to set its design standards quite tight in terms of RAM for things like clock timing, latency and so forth.

"Value" RAM lines are in fact the exact same modules as used in companies better, machine-specific or configuration-guaranteed modules, but the value RAM failed the stringency QC testing required to make the higher level product cutoff.

All RAM tends to start out the same, and then the level of quality specificity or guarantee is based on various QC testing - the "good" stuff that places like Crucial or Kingston or OWC sell as system-specific passed or exceed all QC test limits as specified by the computer manufacturer. The value or non-system specific stuff is the stuff that did not make the grade for the higher QC standards (but it still may be okay in a system that allows sloppier specs than a higher end system like an Apple logic board's requirements).

Hooray! That's why you'll see us trying to steer people away from any 'value' RAM and suggesting Crucial or OWC (Crucial being my 'preferred' brand!).

Happy computing,

Clinton