I've got a new hard drive that supports Automatic Acoustic Management (AAM).
I can only set it to 128 (quiet) and 256 (performance). I definitely can hear the difference.
When I run HDTune I see a difference in access time (16.2 vs 11.2ms, respectively) but my transfer rates and burst rates are identical in both modes (average 112 MB/s burst 231 MB/s...it's an SATA 6.0GB drive/controller).
So here's my question: am I going to notice any sort of real-world performance improvement running the drive at the 256 setting? (The system is primarily used for browsing, office, photoshop, etc.)
So, it is my system disk. What kind of performance improvement would I really feel? Are programs going to open faster, run faster? The system boot up and shut down faster? Are we talking about a second or two or dozens?
Booting involves more things than just reading from your HDD; some parts are 0% disk bottlenecked. So the overall effect of your 30% less disk performance would not translate into 30% slower booting.
But, launching an application should be close to this, especially on a well used system with a decent amount of fragmentation.
However, if you prefer it being silent, then you may opt to just live with the lower performance. Its not like 20% faster or slower would change your experience all that much. Going to an SSD would be a huge step, can be 10.000% (100x) faster than HDDs in some realistic scenarios. But again, that would mean other bottlenecks would present itself; it would not mean things go 100 times faster.