Recently, many motherboard manufacturers have released BIOS updates for their products with a processor socket AM4, which provide support for the new Ryzen 3000 processors. Gigabyte was no exception, but their updates received one very interesting feature - they provide some boards with support for the new PCI interface Express 4.0.
This feature was discovered by one of the Reddit users. After updating the BIOS of the Gigabyte X470 Aorus Gaming 7 Wi-Fi motherboard to version F40, it became possible to select the βGen4β mode in the PCIe slot configuration settings. Tom's Hardware confirms this report and notes that in the previous F3c BIOS it was not possible to select PCIe 4.0 mode.
Unfortunately, Gigabyte has not yet officially announced support for PCI Express 4.0 in current motherboards based on 300-series and 400-series chipsets. Because of this, at the moment it is difficult to say which boards will receive support for a faster interface, and what restrictions there will be in general. And they certainly will, because additional bandwidth is unlikely to come from nowhere.
At the beginning of this year, AMD itself announced that, under certain conditions, motherboards based on 300-series and 400-series chipsets will be able to support PCIe 4.0. However, the company left the implementation of this feature to the discretion of motherboard manufacturers. That is, the manufacturer himself is free to choose whether he wants to add support for a faster interface to his boards. And AMD also said that most motherboard manufacturers are unlikely to care about adding PCIe 4.0 to their current solutions.
In any case, PCIe 4.0 support will be limited on existing motherboards. It is reported that in order to βturnβ PCIe 3.0 into faster PCIe 4.0, the length of the line from the slot to the processor should not exceed six inches. Otherwise, physical restrictions are already imposed. For PCIe 4.0 to operate over longer distances, new switches, multiplexers, and redrivers are needed to support faster signaling.
It turns out that only the first PCI Express x16 slot, located closest to the processor socket, will be able to provide support for a faster interface. Also, slots connected to a PCIe 3.0 switch will not be able to support PCIe 4.0 standards. All PCIe lanes connected to the chipset cannot be upgraded to a newer version either. And of course, for PCIe 4.0 to work, you will need a Ryzen 3000 processor.
As a result, it turns out that PCIe 4.0 support can only be added to current motherboards in a rather limited form and not on all motherboards. It can rather be called a pleasant bonus that some owners of systems with Socket AM4 will receive. Full support for the new standard will be provided only by new motherboards based on 500-series chipsets.
Source: 3dnews.ru