I'm starting to find this really frustrating, there's next to no information about which cards are and are not compatible with the 785G chipset to enable Hybrid CrossFire on AMD's website.
I was planning on buying an Asus M4A785TD-M EVO motherboard which has the 785G chipset and Integrated Radeon HD 4200 graphics, then pairing it with a 1GB Sapphire HD 4650 Radeon discrete card to enable Hybrid Crossfire and have both the onboard and discrete GPU's working together... the main reason I thought this would be possible was from the below sources and on these pages there are graphic diagrams which appear to be taken from AMD's website (though in reality I've no idea where they come from):
http://www.tomshardware.co.uk/amd-785g-chipset,review-31647.html
Graphic Diagram:
http://media.bestofmicro.com/X/2/218918/original/785G%20components.jpg
This is backed up by:
http://techreport.com/articles.x/17328
Graphic Diagram:
http://techreport.com/r.x/amd-785g/block.jpg
Both diagrams clearly show adding either a HD 4350, 4550 or 4650 card for faster graphics, though the reviews don't really go into it. The implication of this shows that this will enable faster graphics with one of those discrete cards assisting the IGP, but if the IGP becomes disabled when any of these cards is connected then you might as well use ANY card, either ATI or NVidia, as long as the spec is higher than that of the 785G HD4200, then of course you will have better graphics, which makes me wonder why specify just those 3??
ATI/AMD's website doesn't really talk about the 785G chipset, they only concentrate on the 780 and 790 when talking about Hybrid Crossfire:
http://game.amd.com/us-en/crossfirex_hybrid.aspx
And again when they do mention the 785G, no mention of which cards can be used to enable Hybrid Crossfire:
http://www.amd.com/us/products/desktop/chipsets/7-series-integrated/Pages/amd-785G-chipset.aspx
There is a handy Crossfire compatibility chart, but it's only aimed at Crossfire and the 780/790 chipsets, not Hybrid Crossfire indicating that AMD/ATi would much rather sell you 2 graphics cards instead of 1
http://game.amd.com/us-en/content/images/crossfirex/CF_combo_chart.jpg
There is one page on AMD's website which may very well be the holy grail I am searching for, explain absolutely everything, answer any questions that anyone could possibly have about this technology and clear up the confusion, but I've been going to it for the past month now and it always says "An unexpected error has occured":
http://www.amd.com/us/products/technologies/ati-hybrid-graphics/
I'm almost tempted to buy an Intel/NVidia based system out of spite for wasting so much time trying to find the right information.