Extremely poor performance and high temperature SSD Plus 240 GB

Sandisk SSD Plus 240 GB.  I’ve probably installed close to 50 of these over the last several months in client PC’s as upgrades from mechanical HD’s.  Overall, they seem to provide good value especially on older PC’s that only have SATA II capability.

However, the last two of these drives that I purchased off the shelf at Best Buy about 2 weeks ago perform markedly slower and run at a much higher temperature than similar units that I’ve installed recently.  The affected units are SDSSDA-240G-G25. The serial number for one of the drives is:  162025478505 and the WWN is: 5001B444A4BF50AF  The drives are marked made in China if that matters.

I use a dual slot Inateck USB 3 external caddy to clone to these drives.  Normally I see writes at around 200 MB/sec or better when cloning.  With these last two drives, I’m only seeing writes at around 40-60 MB/sec and the drive temperatures can easily reach 70 C when monitored using Crystal Disk Info V7.  Other drives  (such as Toshiba Q Series Pro 256 GB, PNY CS2211 480 GB) still clone normally using this same caddy and data rates can be as high as 300 MB/sec and drive temperatures are always 40 C or below.

I also tested using file copies from internal SSD to a single SSD Plus drive plugged into the Inateck caddy.  File copy rates bounce between 60-120 MB/sec and temperatures on the SSD plus quickly climb to 72 C.  Other drives such as the two brands listed above copy at much higher rates and the drive temperatures remain below 40 C (using Crystal Disk Info V7.0)

So the question I have is did I get a bad batch of drives?  If I were to speculate my first thought would be that these drives are missing some type of thermal pads internally and overheat and quickly throttle to a low performance state.  I don’t want to void the warranty by opening them up but it sure seems to me that something major is wrong with these drives.