I have downloaded the manual for the P7P55D-E and found the IO Level Up button either enables 500 MB/s transfer rates for USB 3.0 or SATA 6.0 Gb/s, but not both at the same time, while limiting the PCIe 2.0 graphics card slot to 8x mode.

According to the P7P55D-E Pro and P7P55D-E EVO manuals, these motherboards use a PCIe x4 bridging chip (PLX chip) to provide a similar function. From what I have read on some other web sites, this chip makes use of 4 of the PCIe 1.0 lanes. The PCIe 2.0 slots are remain 1 @ 16x mode or 2 @ 8x mode.

My questions:

1. Does the PLX chip provide USB 3.0 and SATA 6.0 Gb/s transfer rates at the same time or does it only allow one at a time?

2. Does the PLX disable or limit the number of PCIe 1x slots available on the motherboard?

I am trying to decide between one of these motherboards and a i5 750 processor or a P6T with the X58 chipset and i7 920 processor.

Any input is appreciated. Thanks.