memtest86+: if PC3L-12800 (1600MHz) passes at 1330 MHz, is it good?

Hi, folks:

Using memtest86+ to test a new pair of 8 GB sticks of RAM for total 16 GB. It’s PC3L-12800S 1.35V (1600MHz)
It passes when run in an older laptop, running at 1330 MHz (and probably at 1.5V).
is it good?

I can’t currently test it for more than a few hours in a slightly newer laptop that supports 1600 MHz memory, because we’re having hot weather and that laptop registers high temperatures. At some point during testing the screen stops displaying the tests, even though memtest86+ is still running (as I can cancel it with Esc key). I believe I need to clean dust out of that laptop and apply new thermal paste.

As the RAM runs without errors in the older laptop running at 1330 MHz, does that mean the RAM is good? Or, is it possible that it could have errors when run at 1600 MHz?

It's possible that it would have errors at 1600.

That's not to say that it will.