I've got two questions. I'm planing on buying Gigabyte A55M-S2HP and I have a question relating the RAM channels. It has 4 RAM slots that work in dual channel. I have a friend who can sell me 4 identical 2gb ram modules. Will they work on the motherboard? and will I get at the end 8 gigs of ram working at the same frequency?
The second question is this: The MB is FM1 socket, I am planing on buying the A8 3870(or 3850). This processor has an integrate graphics chipset thats preety good. I know i can use it in hybrid crossfire but I dont know what what model of AMD cards. I've got laying arround the house a Sapphire HD 4650 1gb ddr2 126 bits video card. Will this video card and the a8 3870(3850 ..same graphic chipset) work in Hybrid Crossfire?
The AMD APUs are best described as "amateurs of all trades". Despite being innovative and interesting they've largely failed to see widespread adoption. Ultimately they don't provide enough compute power for those that need computer power and they don't provide enough graphical performance for those that need graphical performance. They sit in no-man's-land with no clear purpose outside of extreme budget computing.
Unless you're on the strictest of all possible budgets I advise that you get an Intel i3 platform instead as this will provide far more horsepower than any AMD APU. Combine this with an AMD Radeon HD 7770 and you will be set for some time.
As far as I know there are no IGPs that can be paired with the HD 4650, so that card would be pretty useless. Crossfire is also very hit and miss across the board. Even with two of the best cards it's a complete toss-up as to whether or not it will actually work on a given game.
EDIT: As for that RAM, you would have to make sure that the memory modules are the same type as that which is supported by the platform that you end up buying. DDR2 modules cannot be used in a motherboard that supports DDR3 and vice versa.
In 'hybrid crossfire' (AMD now calls it Dual Graphics) your best operation comes from syncing-up the APU gpu core clock and memory speed with the discreet core clock and memory speed. Best performance in dual operation is also gained from using system RAMs at 1600MHz, and up.
The graphics engine on a Llano APU is an Evergreen "Redwood" with the core clock reduced to 600MHz from 775MHz. The good news is you may over-clock the APU graphics engine and reclaim much of that lost speed -- the bad news is the "Redwood" graphics is essentially an HD5670 and will not work very well in dual-graphics with an HD 4650 with DDR2. An HD5670 is the card of choice for dual-graphics with Llano.
BUT, a "Turks" discreet GPU like the HD6570 DDR3 when synced-up with the APU should perform quite well in most cases.
WIll this work well in hybrid crossfire PowerColor HD6670 Graphics Card 1GB Dual Link DVI-D HDMI VGA DDR3
IF that HD6670 has DDR3, then, yup.
Because of the higher clocks/memory speeds, the HD6670 likely will not sync-up as well as an HD6570/5670 would with the APU graphics engine. It may seem a bit counter-intuitive, but choosing a more potent discreet for dual-graphics normally results in less performance and/or lag/jitter issues.