Common Options : Enabled, Disabled

Details

The ISA bus is slower than the PCI bus. So, when the PCI bus needs to write to the ISA bus, it has to wait till the ISA bus is ready. Because the ISA bus (16MB/s) is many, many times slower than the PCI bus (132MB/s), the PCI bus is stalled for a long time whenever a PCI cycle to the ISA bus is initiated. This really slows down the PCI bus and causes problems for time-critical applications like real-time video-editing.

To prevent the PCI bus from stalling every time it tries to write to the ISA bus, many chipsets now come with an embedded 32-bit posted write buffer that supports delayed transaction cycles. This buffer is designed to store PCI-to-ISA writes so that the PCI bus can be released to perform other transactions. The buffer contents are then written to the ISA bus when it's ready.

Note that the data won't get to the ISA bus any quicker although it's immediately written to the write buffer. This is because the write buffer still has to wait until the ISA bus is ready before it can write to it. But by releasing the ISA writes to the buffer, the PCI bus is freed to do other work.

The Delayed Transaction feature controls the operation of that embedded 32-bit posted write buffer. If enabled, all PCI-to-ISA writes are buffered and the PCI bus is released after writing to the buffer. If Delayed Transaction is disabled, the PCI bus will bypass the write buffer and write directly to the ISA bus.

It's highly recommended that you enable Delayed Transaction for better PCI performance and to meet PCI 2.1 specifications. Disable it only if your PCI cards cannot work properly with this option or if you are using an ISA card that is not PCI 2.1 compliant. Note that Delayed Transaction is only important if you are actually using an ISA card. It is of no consequence at all if you are not using any ISA cards or if your motherboard doesn't even come with ISA slots!