I understand the OptiPlex 7040 having Intel's Skylake chipset running Windows 7 32bt will show a reduced amount of useable memory. I have applied the latest BIOS updater which states it will increase this which it does but not by very much.
Is there any way to increase this further?
No. 32 bit limits haven't changed in over 20 years.
The 4 Gig Chunk broken up by 512 to 1 Gig memory/IO map goes back to the 386 processor and windows NT.
This has nothing to do with the limitations of 32bit. On an earlier model e.g. OptiPlex 9010 with 4GB RAM the useable memory is 3.43GB. However the 7040, with Skylake chipset, only makes 2.53GB available.
This has everything to do with 32 bit and the fact that new Skylake Chipset Memory controller is built into the CPU and the Integrated HD Graphics Steals 1.47 Gigs of the 4 gig 32 bit memory map to support 4k video. Ancient chipsets used as little as 8 megs of ram.
So what you are saying that the integrated HD graphics is stealing 1.47GB of the RAM and as such is causing the issue. However as Dell have already issued a BIOS update to address this, which hasn't made an acceptable difference, can someone from Dell tell me if there is any way to address this or if they are still working on it please.
This isn't ever going to be "fixed" because the issue is 32 bit memory addressing. Ancient Chipsets like the 945G on Optiplex GX620 can address 3.50 gigs ram max. You do not get any system ram back when you add a PCI-E video card.