Inconsistent ripping speed, why?

[spmc]

I have seen this topic discussed in different threads and I have searched old threads but I have yet to find a definitive answer.
I have a 16x DVD ROM drive. Using DVD Decrypter in ISO mode one disk will rip at 12x or 13x, then the next will only rip at 3x. Later I might have one rip at 10x and then one rip at 2x. I cannot make out any pattern with disk content or encryption status either. The other day I ripped a single sided disk with encryption and it ripped at 13x. I then put in another single sided disk not encrypted and it ripped at only 3x.
I have noticed similar rip time differences when using File mode also.
I always check to make sure DMA is enabled and it always states it is (unless it slips into PIO mode during ripping and then back to DMA when finished, if that's possible).
Though I don't use my burner drive to rip much, I notice the same speed variations with that drive also.
Anybody know the why of this? I am curious.

[defense]

this isn't a common problem. You may have something interfering with your DVD ROM or a problem on that channel or maybe even with your ROM. Your results are too sporadic. I get between 12-15.4x on every single...single-layered DVD I rip unless it's scratched..then it may slow down at certain points but not for the entire rip. I get up to 9.4x on DVDRs which i'm thrilled with...and I get about the same with dual layered DVD's... 9-10x. It's normal for the ripping process to increase and decrase during a rip on occasion..but it's not the norm to have your rip speeds dramatically drop and increase like you are seeing.

Try to reboot your pc before a rip and do nothing else. Then just try to rip....see if that helps. I would say it could be a disk..but it happens too often for you...so it seems like some type of conflict or your DVD ROM is unstable.

[ta2]

Some DVDs have a read limit of 10.08Mbps...

Thats about 2.3x

[defense]

Some DVDs have a read limit of 10.08Mbps...

Thats about 2.3x

You're a little confused there ta2...you're talking about bitrate...that has nothing to do with rip speeds.

[t30t28t16t12]

I too have the same problem. My first experience ripping a single sided, non-encrypted @ 2x using DVD Decrypter.

Could it be software bug? Firmware bug? DVD Disc bug (LOL)? Or my beloved Pionner A05 is failing ill?