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P55A-UD3 and Graphics Cards

OK gang, I need a hand here understanding a feature of my motherboard. I've read that it's Crossfire X compatible and that it should work well when/if I run my 2 XFX 4770's in that mode. I know they are lower end cards and I probably am worried about nothing, but I've also heard that if you run SATA III and USB 3 you will lose 4 lanes from the PCIEx16 channel and basically make crossfire useless. I've also heard that it will disable the second card if you use SATA III and USB III simultaneously. I mean, this doesn't make sense to me. What if I wanted to crossfire a better card? Say a 4890? Can someone please shed some light on this, or more information on how the P55 works in general?

I am no noob, but I am no genius either so I guess "dummy talk" would be the best answer. My twin brother is using my rig with my 4770's so throwing them into my P55A-UD3 isn't an option at the moment. That would probably be the most direct and efficient way of testing to see what bandwidth I would be running at. But I just am looking for answers and experiences folks have had.

Any comments are welcome.
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  1. when dual gfx are used , the sata and usb work in 2.0 mode , it does not disable the second gfx at all ...

    u will have :-

    single gfx card at x8 , sata3 and usb 3 at full 3.0 speed.
    dual gfx cards at x8 each , sata and usb will work in 2.0 mode , like previous gen ports .
  2. but wait , the ud3 has the second pcie as x4 only , of the p55 chipset .... the above post is applicable to p55a ud4p ...

    for ud3 , it would always be single card at x8 , second card at x4(CF not recommended) , and sata and usb at 3.0 .

    gigabyte takes the bandwidth from cpu's pcie lanes for the new sata/usb , asus takes this bandwidth from p55 chipset .... asus is a better solution , as u can get dual x8 + sata/usb in 3.0 speed , but as they use a plx bridge chip with the p55 chip , their mobo's are somewhat costlier ...
  3. i hope this helps !
  4. Not really. My single card in this board is reported as running at 16x when it's stand alone at the moment. So it looks like your wrong.
  5. no , you have not yet connected 3.0 devices then :-

    see the red colored notes a the bottom of this page :
  6. Everything is USB 2.0 that I have. Mouse, Keyboard, Webcam, External 1TB hard drive, Mic, Wireless Adaptor, iPod, Printer, Game Controller. And still says I'm running x16. Do you have this board or are you guessing?
  7. Best answer
    even when u do connect a 6gb/s hdd or a usb3.0 disk , the x8 will be enough for most single gpu cards , never use dual gpu card for example the 5970 in it .
  8. the ports need to be connected to a 3.0 enabled device to make them work in that mode , otherwise the gfx work at usual 16x .. of course , ure using gpuz for the mode check , isnt it ?
  9. Yeah, of course! I don't think I'll be running sata III or usb III any time soon so I guess I should leave this thread alone and just be happy with what I have until maybe summer when I upgrade again.
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