Direct3D Initialization - Introduction to 3D Game Programming with DirectX 9.0 - page 41

D3DFMT_A32B32G32R32F —Specifies a 128-bit, floating-point
pixel format. Starting from the leftmost bit, 32 bits are allocated for
alpha, 32 bits are allocated for blue, 32 bits are allocated for green,
and 32 bits are allocated for red.
For a complete list of supported pixel formats, look up D3DFORMAT in
the SDK documentation.

Note: The first three formats ( D3DFMT_R8G8B8 , D3DFMT_X8R8G8B8 ,
and D3DFMT_A8R8G8B8 ) are common and supported on most hard-
ware. The floating-point pixel format and some of the other formats
available (see the SDK docs) are not as widely supported. When using
these not-so-widely supported formats, be sure to verify that your card
supports a particular format before using it.

1.3.4 Memory Pools
Surfaces and other Direct3D resources can be placed in a variety of
memory pools. The memory pool is specified by one of the members of
the D3DPOOL enumerated type. The memory pools available are:

D3DPOOL_DEFAULT —The default memory pool instructs
Direct3D to place the resource in the memory that is best suited
for the resource type and its usage. This may be video memory,
AGP memory, or system memory. Note that resources in the
default pool must be destroyed (released) prior to an IDirect-
3DDevice9::Reset call, and must be reinitialized after the reset
call.

D3DPOOL_MANAGED —Resources placed in the manage pool are
managed by Direct3D (that is, they are moved to video or AGP
memory as needed by the device automatically). In addition, a
back-up copy of the resource is maintained in system memory.
When resources are accessed and changed by the application, they
work with the system copy. Then, Direct3D automatically updates
them to video memory as needed.

D3DPOOL_SYSTEMMEM —Specifies that the resource be placed in
system memory

D3DPOOL_SCRATCH —Specifies that the resource be placed in sys-
tem memory. The difference between this pool and D3DPOOL_
SYSTEMMEM is that these resources must not follow the graphics
device's restrictions. Consequently, the device cannot access
resources in this pool. But the resources can be copied to and from
each other.