Windows – System does not show all installed RAM even though CPU-Z detects it

Most CPUs support a limited number of memory ranks.
Most consumer DIMMs are dual-rank (this is the most economical solution).

However there are also single rank DIMMs and quad-rank DIMMS. The difference betyween these is rather technical (and I had to look it up myself about a year ago), but it seems to come down to this:

• A CPU likes to have more memory channels to make things faster.
• This can be done with more DIMMs (seel dual-, triple- or even quad-channel CPU's), or by using one physical modules with 'sort-of' the content of two DIMMs on one stick.
  This is the rank.
• Most systems use dual channel dual rank memory. (two DIMMs, each with two ranks).
• A CPU can only drive a limited number of ranks. (Think of it as each rank draining the address bus a bit. More ranks is more draining. This limits how many ranks can be used, though sometimes more ranks can be used at a lower speed.

This (https://serverfault.com/questions/69612/dimms-single-vs-double-vs-quad-rank) might be interesting reading to grok the background.

But to answer your question:

My laptop is capable of supporting up to 32 GB.

That simple is not enough information. To answer it with any certainty we need something like:

• My laptop is capable of supporting up to 32 GB.
• In four DIMM sockets.
• With a maximum of X ranks
• And at a voltage of a.bc per DIMM.

My best guess it that it will work.

Depending on he chipset you may and up with:

8GB DIMM 4+4) First part of the 8GB DIMM Only in dual channel mode 4GB DIMM (4)

4GB DIMM (4) In dual channel mode 4GB DIMM (4)

Or with no dual channel mode at all for 12GB of your memory.

Note that the ranks at this point are mostly about 'will it work', and the channels are about 'will I get the 5% average speed increase from going dual-channel`.

Would triple or quad channels have only 2 color variants or would there be more colors?

Not more colours, but a larger set of sockets in the same colour. E.g. a X58 based board (triple channel) would typically give you 6 sockets. 3 coloured blue and 3 coloured white.

• The X58/i920 has three memory controllers which can be used simultaneously.
  (aka triple channel).
• Memory controller #1 is connected to DIMM sockets A1 and 1B.
• Memory controller #2 is connected to DIMM sockets A2 and 2B.
• Memory controller #3 is connected to DIMM sockets A3 and 3B.

Since a typical consumer setup has a memory controller which can handle up to 2 dimm sockets^* this translates to 3x2 memory banks. You want to use all memory controllers at the same time, so you put one DIMM on each memory controller. This set has the same colour.

The typical setup can handle two DIMMS per memory controller. So you get a second set of colours.

In a consumer quad channel setup you would expect two sets of four. So two colours and 8 DIMM sockets.

In a server setup you will find more sockets per memory channel. E.g. my home server (A Dell R300) has 6 DIMM sockets. It is dual channel. So I got 3 sets of 3. Which is logically quite different from the two sets of three in my home desktop.

Based on this you can easily extrapolate for other configurations.

^*Or rather up to 4 ranks. One regular consumer DIMM counts for 2 ranks, so that translates to 2 DIMMs. In server based boards this is often different, but that comes at the cost of speed.