OSDev.org

Hello. I have an asus rampage iii extreme edition motherboard with Intel(R) Core(TM) i7 CPU processor and intel x58 chipset.
My BIOS has not an option to change the Maximum Payload Size in the PnP/PCI setting. I can see that all my PCI Express (such as NVIDIA Graphic card, a Xilinx board) devices use 128 byte as payload size. I have connected them to the fast PCI Express ports. From the datasheet of the chipset i have seen that the payload size must be also 256 byte for these ports. Why my devices use the 128 byte payload size? Can anyone help me?

I believe that manufacturer of my chipset has set the payload size in 128 bytes and i can not change it but i'm not pretty sure. Does anyone sth about it?

The likely answer is no, nobody does. It takes too much money to get the "available" specs, and all the others are covered with nondisclusure agreements.

That said, motherboards and chipsets are design to work independent of whether an operating system has a driver yet for them (because even if it does, can the operating system fix the bios before the bios breaks the operating system). Therefore there is no problem.

As i said all my pci express root ports have been set in 128 bytes payload size and not in 256. It is strange because my endpoint devices can support 256 bytes for payload. Is it a limitation of the motherboard(asus) or the chipset(intel x58) or there is a mistake by my side?