As far as my knowledge goes, there just hard drives. Swap out the old one for a black caviar western digital, my friend's is silent so im not sure about its reputation. As for the green drives, there slow, that's why apple doesn't use them.
I am afraid with the 2010 iMac it looks to be more complicated, though few people on the tech boards seem to know about it.
I wanted to know why Apple flash the Seagate drive with their own firmware. In the 2010 model said firmware apparently monitors HD temperatures and regulates the speed of the hard drive fan via the temperature sensor built into the Seagate. I imagine this was a cost cutting measure as previously, I believe, in some earlier iMac models, Apple glued a temperature sensor to the hard drive (?) making it a simple enough swap over. Apparently in the 2010 model without firmware even with the correct propriatory lead plugged in for the model of hard drive you are using, said lead, without that firmware, doesn't retrieve needed data, causing the HD fan to spin up to a speed faster than it needs, though this might still be relatively silent compared to what some with noisy Seagate batches are enduring, I don't know. There are some relatively straightforward workarounds talked about in recent postings on OWC's blog and Apple's own forums. One appears to involves a relatively expensive purchase of a temperature sensor (I think around $22) to glue onto the dive in a specific spot, the other some very basic electronics knowledge to prevent the fan from doing this, and also, essentially, a short. There is also a terminal command, I believe, to slow the fan.
I would rather no one quote me on any of this because I have no direct experience of the internals of iMacs, never mind the 2010 model, but instead search out these threads yourselves (are we allowed to link to rival forums? I got in trouble a mild lecture from a moderator on another board for doing that so avoid it). I think this is a developing story. I would think if just swapping out the hard drive did any harm we would know about it long since but I would like to get this right.
Edit - check out OWC's blog entitled 'Proprietary cable can put the brakes on upgrading Late ’09 iMacs' not the OWC's talk about different hard drives needing different proprietary cables, though that is interesting, but the comments section talk about the greater firmware issue. The blog was about the late 2009 model but in the comments section people discuss problems with the 2010 model HD temp/fans issue, firmware and workarounds.
