Question about the GA-Z77X-D3H

[Nero22]

I got this from the Gigabyte website about the GA-Z77X-D3H

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1 x PCI Express x16 slot, running at x16 (PCIEX16) (pcie 3.0)
* For optimum performance, if only one PCI Express graphics card is to be installed, be sure to install it in the PCIEX16 slot.

1 x PCI Express x16 slot, running at x8 (PCIEX8) (pcie 2.0)
* The PCIEX8 slot shares bandwidth with the PCIEX16 slot. When the PCIEX8 slot is populated, the PCIEX16 slot will operate at up to x8 mode.
(The PCIEX16 and PCIEX8 slots conform to PCI Express 3.0 standard.)
* PCIE Gen.3 is dependent on CPU and expansion card compatibility.
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I got no idea what it means.

If I crossfire two Radeon 7970 (pcie 3.0) on this board.
Will I get any less performance on this board than the Sabertooth Z77 or P8Z77-V DELUXE?

Is it safe to overclock my i5-3570k to 4.5GHz on this board?

 

[manofchalk]

With two cards on that board, slot bandwidth will be reduced to PCI-2 8x, which is more than enough for graphics cards. You wont be limiting the performance off the Crossfire array by doing so.
Those other boards arent any difference in this aspect.

You should be fine to clock the 3570k that high.