Any ideas for dvd drives' speed being misrepresented?

[Cronoc]

I know this isn't perhaps within the wheelhouse of dbpoweramp, but I've only noticed it due to this program, and I have not found a solution or much conversation about this problem with google searches. While using dbpoweramp ripper (latest version), I've had my disc drives change speeds occasionally. I have a TSSTcorp SH-S223L drive that sometimes is acknowledged as reading at 40-48x, sometimes is stuck at 8x (on a software level, these will be reported in the "technical" button in ripper options). Going to device manager and uninstalling/reinstalling the drive has a very small chance of changing anything, and when it is back to good speeds, simply ripping a few CDs can unexpectedly set it back to an 8x max with no input besides the usual ripping, ejecting and inserting new CDs. But I figured the drive is old, and perhaps there's a driver problem with 64bit Windows 7 so I ordered a new drive.

But I also ordered 2 LG GE24NU40 external USB drives, specifically bought because they advertise a CD read speed of 40x. I got them today, but one was faster than the other at first, though they both were correctly read as having a 40x max speed. Then this happened: (edit: clearer image here:http://imgur.com/ZFiU7vo. At some point, it was decided that one of two identical drives has a max of 10x speed. With them being USB drives (with separate power plugs, so that's not an issue), there are extra possible wrinkles. I'll say that I've tried different USB ports without success, tried uninstalling in device manager and restarting, confirmed that on my good drives the CDs I'm using can be ripped at 20x and higher. Hell, the drive that is now stuck at 10x got to 35x on its first rip. Then something happened... I don't know what. I'm hopefully getting around my problem with the TSSTcorp drive with the replacement, but for these USB drives... well, any ideas would be great. There is no manufacturer's software/firmware for these drives.

I'm on a fully up to date Windows 7 Home Premium 64 bit.

[Spoon]

Re: Any ideas for dvd drives' speed being misrepresented?

The maximum speed should not really change, unless the drive is setting it based on actual CD inside the drive (when a cd is inserted, the drive automatically reads part of the last track and sets the maximum speed for that disc).