My sweet seagate 7200.7 P-ATA is about 1.5 years old, 40Gig, a ST340014A, and basically you can't hear it without considerable efforts. I originally wrote the remainder of this post at storagereview.net, about the 7200.8....
About the noise level and performance of the 7200.8 SATA
I spent a lot of time reading mostly at Tom's Hardware, and a little at Anandtech to choose my new drive: a 250Gig 7200.8, which I've now had for about 4 days. It's my 4th or 5th Seagate, and my previous one a 40 gig 7200.7, about 1.5-2 years old has been flawless in every way and so silent that you can't even tell if it's busy seeking with your ear anywhere except in full contact with the case! Basically the 7200.7 was never audible, and the new 7200.8 has two sounds: a muffled seek sound which isn't bothering me yet, with my summer air conditioning during the afternoon, and even in the quiet morning time. (more on the second sound later.) I've spent a good bit of time and money on this, my second silent computer (A64 3000, with sweet qualities).
But the advantage to the 7200.8 here is exactly that I can tell when it's busy(!), and thus what's going on when my computer pauses. This has become really important to me actually. With the 7200.7 I never knew, and often wanted to know what the heck was causing my computer to pause -- drive bottleneck or some strange system or software thing (I don't know why my nice quality case doesn't have a hard drive light, lol). When you can detect the drive working, then you can know what is happening. So that's a plus for the 7200.8, with it's gentle access sounds.
But....the second sound.....it has at times had an off and on high-pitched pure tone, very high, medium loud, and somewhat piercing. Currently though it has been quite now mostly (98% of the time) for the last hour, which come to think of it, has happened before. Perhaps it matters how long the system is on, and if the drive is fully warm. Perhaps there's a break in period. Overall, since I like the access noise, if the high pitched thing reduces some more, I'll be satisfied quiet satisfied (pun intended).
Performance wise, with very careful testing on my identical software and system after the change over, I find that on the whole average overall the 7200.8 is perhaps slightly faster than the 7200.7 during most days use, although slower a little on bootup (just 3 seconds though). It's a wash, since the bootup and come out of hibernate lack of better performance are important enough to balance the superior large file (read video) performance.
But....the drive is mainly to record and work with video from my TV-capture card as my PVR, so....since it is faster for large file read and and write (significantly, especially for write -- 10 seconds less to write to hibernate for example), I'm pleased enough with the performance on the whole -- it's excellent where it counts and close in the other most other areas, according to about 5 reviews, which hightlight a good performance, echoing mine, with large file loads and writes
So....good qualities as a large video file drive, and let's face it, that's the only reason most of us have for going over 80Gigs to start with!
! Excellent in the only place it really matters for many of us speed wise.
Now I'm thinking I'll bring back the 7200.7 as the system drive for bootup (where it is a tiny bit faster anyway, and use the 7200.8 as the data drive just for video and backups, and get some advantage from using 2 channels anyway. So frugal though I am, I'll not be donating the old 7200.7 to someone else after all. If I scrape together another system for a friend, they'll just have to shell out $60 for their drive!
Fingers crossed about the high pitched, which has been blissfully silent now for a good while.