Admittedly this should only apply to the classic non-DCH driver (so not only it doesn't involve IAC, but there's not even the slightest overlap in hardware that could even support both).. still there ain't a page for that so I'll just dump it here.
Some more or less old games can be particularly adamant/quirky with their VRAM checks, so in order to work these around since 2015 the drivers have a DedicatedSegmentSize setting in HKEY_LOCAL_MACHINE\Software\Intel\GMM (of note that too big values can also cause problems)