I have a problem with upper memory on my Asrock 775i65G board. To be precise, the problem is with the scarcity of it. In the C000-EFFF range, there's just enough room for the EMS 3.2 64 kB page frame, but not much else.

C000-CFFF is all taken by the GeForce 5900 and its 61 kB ROM. Given that EMM386 wants 4 kB aligned blocks, the remaining 3 kB can't be used.

D000-DFFF is usable and EMM386 will creat a page frame here.

The problem is with E000-EFFF. MSD marks the whole region as RAM. UMB-Checker from UMBPCI marks E400-E7FF as usable. DISCOVER (from Helix Netroom/McAfee Utils) is even more specific and marks specific 4 kB blocks as In Use, here's part of the report for the upper memory range:

1|  Segment   0123 4567 89AB CDEF                                              |
2|-----------------------------------------------------------------------------|
3|  0xA000    VVVV VVVV VVVV VVVV                                              |
4|  0xB000    |||| |||| VVVV VVVV    V - Video RAM                             |
5|  0xC000    BBBB BBBB BBBB BBBB    B - BIOS ROM                              |
6|  0xD000    |||| |||| |||| ||||    + - In Use                                |
7|  0xE000    +||| |||| |+|| |+++    | - Potential UMB                         |
8|  0xF000    BBBB BBBB BBBB BBBB                                              |

Qualitas ASQ matches MSD accuracy: it marks the whole 64 kB E000-EFFF as RAM.

I've launched DEBUG and peeked into the E000. It matches what DISCOVER sees: the blocks marked "In Use" really have some data, the unused are straight 00s or FFs.

The question is, how can I identify what is "using" this RAM so I can see, if it can be disabled? There are some strings, but they are cryptic to me. The first E000 block contains strings like "ACFG" and some data, but not much more. The later blocks contain for example the name of the hard drive (like WD740GB for the Western digital one), but still not much else. There's even a string like ADAPTER.ROM, but there's no additional adapter on this board and neither I'm using one. It's just one HDD connected to the ICH5.

Bonus question: why do some tools mark the whole 16 or 64 kB region as used, while others will go in depth and mark it at 4 kB granularity? Should I expect problems if I include the free 4 kB blocks to EMM386? I know the Last Byte Memory Manager could go even finer and use even smaller holes, but I assume this was because it had its own drivers for buffers, files etc. and could use these effectively.

Any other tools you recommend to check what's going on in upper memory?