There is more to raw data transfer rates than just the spin speed, in the same way as there is more to CPU performance than its clock speed.
The data density levels per track, the firmware, the caching, the processor, the algorithms the accuator arm - they are all very important for the drive performance and its noise characteristics.
Seek times/noises.
Apart from rotational latency (spin speed), there are several things that make a drive access data faster or slower than its counterparts, the accuator arm speed is what you hear as "seek noise", the accuator arm moves at "blur speed", the faster its acceleration, speed and stopping the faster it will get to the data. This is exactly the same as someone in a car, but just like car driving there are other elements to overall performance. However the faster its acceleration, speed and stopping the louder and sharper the seek noise will be, which is the main reason why quieter seeking drives are slow seeking drives, they take a lazy approach to getting to the data, maybe 1.5 rotations instead of 0.5
If the accuator arm has got to the correct position to read/write the data it is then waiting for the disk to spin the disk round to the right position so it can actually read the data. From the noise perspective there is no point in rushing, if you have the time take it so the seek can be quieter.
If there is a que of data waiting to be read it is better "overall" to read the data in a "shorter time to each piece of data" technique rather than reading them in the order of requests. i.e. read A-B-C-D-E as thats how the data is spread accross the drive, rather than 4-1-5-2-3 as the requests might be, this allows the drive to make much shorter seeks (physically) but this will also slow down the requests. As A=1 and 5=E, 1 gets a good deal, but D has to wait three requests before the data is retrieved from the drive. Most of the last paragraph is down to the firmware and the algorithms.
You will find that a fast seek time and a high data transfer rate dont always mean a fast drive in real world usage, as there are an awful lot of thing going on behind the scenes that the manufacturer never tells anyone. Likewise synthetic benchmarks are worthless simply because the drive manufacturer can make their drive do very well in that, but might be total crap in th real world (I am cynical).
Likewise manufacturers like Seagate and Samsung who have very high "sequential" data transfer rates use this to their advantage in the algorithms and caching, because they have slow seek times. Other drives have fast seek times but slow data transfer rates, so again they use the benefits of their drive in their ultimate design.
I am no drive genius, but thats most of what you need to know from a quiet PC perspective.
Hypothetical question: If I had two physically seperate hard drives and accessed one file on each at the same time, would it still crawl like my computer does now?
If it would, why? What can be done to fix that? Different busses in the mobo?
If it wouldn't, how many seperate drives could I use? 4? One per SATA port?
No. The 2 drives are seperate entities and so longs as your CPU can keep up (fast single core or any dual), you wont have a problem.
The problem is that you would need to spread your data and programs accross one or more drives, I experimented with this an awful lot about 5 years ago, I had my OS and "Swap File" on one HDD, my programmes and games on another, and my data on a third drive.
This meant (in theory) that If I load a program when my PC is busy (high swap file usage) both drives will be doing different things at the same time (I had a dual CPU system so it was OK with that), I could then fire up a CD-ripping promram and rip data to a third drive.
It worked - it was far quicker than using 1 drive, but that was only the case because I had a dual CPU rig, most systems of the time would not have seen the benefit. But again, to put this into perspective, the way that HDD's work is very different now compared to several years ago. In real terms yes you will get a faster performance by using a similar setup now, but it wont be the quantum leap that I experienced.
The reasons are:
RAM is cheap, you will find a far bigger performance jump by using 2GB of RAM and dissabling your "Page file" rather than having your "page file" on another drive, it is also far quieter.
Drives are so much faster now that once your program has loaded (quicky unless its really big) the drive is waiting for you to use it for data and as you have loads of RAM your drive doesnt need to swap data out to have RAM space to fully load the program into RAM.
Unless you are doing something that is very drive intensive you shouldnt really need more than one drive, are you video/music editing, RARing/unRARing files.???
I have a PC at home that has a 2.5" drive, its got reasonable performance for its tasks, but its drive performance is about half the speed of my main PC and its boot/programmes/games/data 400GB T133 drive which I rarely have to wait for it to do anything, unlike my 2.5" machine which is very slow the moment I ask it to do more than one intensive thing. Movies dont stutter or jump at all when I am unRARing in the background though.
Andy