SC Tom wrote:

Years and years ago, there used to be these adapters that you could
plug 2 sticks of RAM in to increase the amount memory in each slot
(had some on an old 386 or 486 PC). Are they still being made that
would work on DDR3 RAM, or are the newer memory speeds making that
unstable? I have a number of 8GB sticks around and would love to bump
my desktop from 16GB to 32GB, just for grins 'n giggles (and without
spending big bucks on 2 16GB sticks).

Each mem slot is rated for a maximum capacity based on several factors,
one of which is the number of address lines. Rarely are mobos
overbuilt, and if they were then they would support bigger capacity
modules. You'd have to look at the specs for the mobo where you want to
try this gimmick to see what is its rated max capacity for a module. If
the mobo was designed for 8GB sticks, it doesn't have another address
line to support 16GB sticks.

You never mentioned the brand and model of your mobo, or which CPU is
installed. Go check their specs to see what is the max size of memory
module is supported. Sticking an adapter card into a slot won't make
another address line magically appear or the controller support larger
sticks. The extra address lines may be physically present, but that
doesn't mean they are logically enabled. Limiting the size of memory is
how makers can lure consumers to spend more on mobos with larger memory
capacity. They can even use the same controller and traces to build
multiple mobo models with differing memory capacities, and just use the
firmware to decide how much gets supported. They economize on the
tooling and parts needed to build the various models, but target
different pricing points for consumers that want to shave a little bit
by not paying for the max capacity.

You also never mentioned which OS you are running on your computer.
Besides limitations (real or throttled) in the hardware, there are
enforced restrictions in max memory capacity that vary by the version of
Windows.

Windows XP Home: 4 GB
Windows XP Professional: 128 GB
Windows Vista/7 Home Basic: 8 GB
Windows Vista/7 Home Premium: 16 GB
Windows Vista Business/Ultimate/Enterprise: 192 GB

https://docs.microsoft.com/en-us/win...ndows-releases
Shows more Windows versions and their artifical throttle on their
supported maximum memory size.

Like a flooring or least() function, you get the minimum of the maximum
memory capacity between the hardware and the OS.