Radek,
The PXIe-PCIe8388/9 only uses 2 MB of address space (technically it doesn't use RAM, but it uses address space which may limit how much of your RAM is available).
I'm not sure whether you're assuming the 8388/9 is using the RAM because there's not much left, or whether you're looking in Windows device manager and seeing what it's reporting as "resources".
Less technical explanation
The 8388/9 is actually just forwarding address space for devices behind it. So the consumers for the RAM's address space are all the things in the chassis. You can test this by removing devices from the chassis and seeing that your RAM increases.
More technical explanation
PCI and PCIe devices request address space. PCI bridges (or PCIe switches) above the devices are configured to forward accesses to them when the access matches the address space of the devices. The address range the bridge/switch forwards is called the "forwarding range," and device manager will report it as one of the "resources" consumed by the bridge.
For example, if there are 10 devices that each request 8 MB, the switch above them will be configured to forward an 80 MB window. Device manager will report that the switch uses 80 MB, even though the switch is forwarding it to other devices, not consuming it. Device manager will also report that the devices each use 8 MB.
I hope that helps you understand what's happening so you can figure out what's actually using your RAM space. Can you use a 64-bit OS?
- Robert
