[achtung]

This is something that has bugged me for the longest time.

Is it faster to install applications to another hard drive and run them from there, or install them on the same hard drive your OS is on?

Specifically, would it be faster for me, using a couple SATA II hard drives, to install most of my applications on a second one, and use the first one for OS(s)?

[Descenterace]

It will make zero difference, unless the apps in question transfer colossal amounts of data between memory and disk, and even then it makes more sense to just put the data files on a different disk.

If you're running a database application or a VMware virtualisation environment, put the database itself or the virtual machine on a separate disk and leave the application in the usual place.

[Hippo]

if you're using a hard drive connected directly to the motherboard, you should have no significant difference. the OS should be more or less loaded into memory at the point you're running things anyway, but the only thing i can think of that would certainly slow it down is VRam usage on the disk or using an external/network drive

[Fury]

Like Descentarace said, it doesn't really make that much difference. It only helps if you have more than one application constantly accessing hard drive.

For example, you could install your games on another hard drive to speed up their loading times slightly. But when you play games, you probably are not running any other apps that would noticeably decrease access times anyway. It would probably help more to move swap file and temp folders to another hard drive. But the drive shouldn't be slow, so using an old considerably slower drive for swap file and temp folders is not a good choice.

These days most of you are probably running P2P applications and may even keep them running when playing games. P2P apps often have to access hard drive constantly to write newly downloaded bits and cache bits to upload, so P2P users would benefit from having a dedicated drive for P2P.

[WMCoolmon]

If you're going to have two hard drives, I would suggest that you make one of them a dedicated, 'perishable' data drive. The other would be an applications/system drive. Doing so makes it far easier to back everything up. For example, if you had a more or less identical external hard drive with eSATA, you could dd your data drive to the external drive every weekend. Should your data drive spontaneously fail, you could just plug in the eSATA drive and have instant access to all the backup data.

[Nuke]

photoshop likes to see a few drives, especially when working on large files.that way it can store scratch information supposidly twice as fast. i do what wmcoolmon does but in reverse (well sorta). in my case the parishable drive is the one with windows on it , becaise its more likely to get formatted by me. its only a few gigs, enough to install windows and any apps that might complain and not run if their registry entries arent found. all my data, games (so long as theyre not dependant on the registry), and opensource apps. all of which can run immedeately on insatalling a new os on the drive that is likely to perish due to windows rot.

[Descenterace]

Disk access isn't much of a bottleneck for a workstation. I bought a hardware RAID-5 card for my current  computer (the array consists of 4 hard disks) and noticed almost no speedup in normal use, except that Windows boots about twice as fast.

But in games, I see a decrease of around 70% in loading times. Since Supreme Commander is one of the games I play, that's quite appreciable.

[jr2]

I've heard you can slightly increase performance by making a separate partition for your swap file... prolly .5 - 2 Gigs.