Plextor PX-B940SA 12x Blu-ray Disc Writer - Write Tests and Final Thoughts

Article Index
Plextor PX-B940SA 12x Blu-ray Disc Writer
Specifications and Closer Look
Software, Installation and Info
Media Read Testing
Write Tests and Final Thoughts

DVD Writing Tests:

Now that we've seen that the PX-B940SA is a capable reader, we'll follow up with some writing tests on both DVD and BD-R media.  We used a limited selection of media, but the drives performance seems to be consistent on older media as well as brand new disks.  It managed better than rated write speeds on everything except the BD-R DL media.  It was rated at 4x and the drive fell a bit short of that.

 DVDR - Write
DVD-R - Write
DVDRAM - Write
DVD-RAM - Write
DVDDL - Write
DVD-R DL - Write


I find the write speed of the DVD-R disk very impressive at 5:45 for a full 4.7GB disk.  The average was 11.11x using Constant Angular Velocity recording but you can see that the buffer starts to run down a bit toward the end.   Although our DVD-RAM disk is rated at 5x, the drive wasn't able to write at that speed and continued with a very slow 2.4x speed through the disk.  The Dual Layer DVD-R disk worked a little better at 6x and this is actually quite good considering the media is Verbatim disks rated at 2.4x.  Thankfully, the speed was better than 2.4x.  It still took almost 19 minutes to write the disk.


BD-R SL and BD-R DL Write Tests:

The big thing with a Blu-ray drive is to test Blu-ray disks.  Granted, we all want it to be a well-rounded drive, but if it sucks writing and reading 25GB and 50GB disks, we don't care how well it reads and writes regular DVDs.  We've managed to pull off a couple of tests but our Dual Layer media was limited as it costs $30 a disk here in the Great White North.

 BDR - Write
BD-R SL - Write
BDRDL - Write
BD-R DL - Write


I used Verbatim 4x BD-R 25GB disks as well as TDK 6x BD-R DL disks.  The write performance was less than stellar using Opti Drive Control.  Neither of the disks achieved their maximum write speed and the Opti software actually crashed when I was about 97% through the Dual Layer BD-R.  Thankfully both disks could be read and because the disks were full of random data and not movies, they played back on the drive just fine.  This is something to note though that BD-R disks are not always going to give you the write speeds you may expect.  As media becomes more widely available and as drive firmware matures, this will improve, but a fast BD-R writer is still the purchase of early adopters - and that doesn't always work out as we hope.

In the end, it took over 36 minutes to write a full 25GB disk at an average of 2.54x.  The disk started well, then scaled back just as it approached 3x speed.  Even though the disk is rated faster, the drive scaled back to ensure a good quality disk and in the end, I'd rather have a disk I can read than a coaster that took a few minutes less to make.



This is the first BD-R writer we've had the pleasure of looking at and while they've been around a while, the speeds have certainly increased over the last year as the prices have continued to drop.  This is good news for consumers and once media becomes ~$1.00 for a 25GB disk and $5 for a $50 GB disk, things will really take off.  In the meantime, the PX-B940SA is a good step in the right direction as it offers a full array of media writing and reading capability and can easily be the only optical drive in your system.  Earlier BD-R drives were sluggish when it came to reading and writing DVD and CD media, but this Plextor drive offers great speed across all media types.

The only downfall is that BD-R SL and DL writing speeds were not that impressive.  I bought the fastest Dual Layer media I could find and it never exceeded 3x write speeds.  If you need or just plain want a fast BD-R, DVD-R, CD-R writing drive, the PX-940SA should be on your short list.  It may not be the best drive out there, but according to reviews that I've seen of other drives, it's pretty much on par with anything else that is available.


  • Fast 12x BD-R write speed (rated)
  • Full software bundle
  • Excellent warranty support
  • Fast reader and writer of all media (tested) except BD-R
  • Support for +/- DVDs, CD-R, CD-RW, BD-R, BD-RE media



  • Wasn't able to write BD-R SL and DL media at rated speed
  • A little expensive compared to other similar drives
  • 12x BD-R media not available so fast speeds are moot at this point





I'd like to thank Plextor for sending over the PX-B940SA for us to review.  If you have any questions or comments, please post them at the "Comments" link below.