Leaker details everything there is to know about Alder Lake's Z690 platform
Will PCIe 5.0 be a useful feature?
Published: 10th September 2021 | Source: PC Inquisitor |
What should we expect from Z690?
Intel will launch its 12th Generation Alder Lake series of processors later this year, arriving alongside a new LGA1700 socket and new 600-series motherboards and chipsets.
PC Inquisitor has released an image of an Intel LGA1700 processor alongside a detailed block diagram for the company's Z690 motherboard chipset, confirming many of the specifications of Alder Lake and the capabilities of the company's flagship 600-series motherboard chipset.
For starters, it has been reconfirmed that Alder Lake will support both DDR5 and DDR4 memory types, supporting standard DDR5-4800 data rates and DDR4-3200 memory speeds. Intel's Alder Lake platform will reportedly automatically run DDR5 memory in Gear 2, and Gear 4 mode, which will run Alder Lake's memory controller at 50% and 25% speeds to cope with the data rates offered by DDR5 memory modules. Overclockers may be able to get the CPU to run at a lower memory gear mode to reduce memory controller latency. It is likely that Z690 motherboards will support either DDR4 or DDR5 DRAM. While a motherboard that supports both is possible, such hybrid motherboards shouldn't work using both memory types at once.
According to the block diagram below, Alder Lake will feature 20 CPU PCIe lanes and a PCH chipset (DMI 4.0) connection that operates at PCIe 4.0 x8 speeds. Sixteen of Alder Lake's CPU PCIe lanes are PCIe 5.0 compatible, operating either as a single x16 lane or two x8 lanes. The remaining four PCIe lanes are PCIe 4.0 lanes intended to be used with M.2 SSDs.
Intel's Z690 chipset will deliver users up to twelve PCIe 4.0 lanes and sixteen PCIe 3.0 lanes. However, these lanes will be pushed through the chipset's DMI interface, which uses eight PCIe 4.0 lanes. This limits the maximum speeds of devices connected through Intel's chipset, but only when many devices operate simultaneously. With its wider DMI interface, Alder Lake will feature many significant connectivity upgrades over Rocket Lake.
Below we can also see that Z690 can support WiFi 6E, multiple USB 3.2 Gen 2x2 ports, and support 5G Ethernet as an optional feature.
Is Alder Lake's PCIe 5.0 support useful?
With sixteen PCIe 5.0 lanes that can be connected using a single x16 connection or dual x8 connections, it is hard to see how PCIe 5.0 adopters will benefit from the standard. Yes, there are "future-proofing" arguments to be made, but by the time PCIe 5.0 becomes a vital feature, won't leading-edge PC buyers be ready to upgrade from Alder Lake to a newer platform?
PCIe 16x lanes are commonly used by graphics cards, which only see limited benefits from today's PCIe 4.0 connections. As such, is PCIe 5.0 compatibility useful here? With Intel's Alder Lake CPUs offering PCIe 4.0 support with its four CPU-connected M.2 slot PCIe lanes, most Alder Lake motherboards won't support PCIe 5.0 compatible M.2 SSDs.
Right now, the only market that's close to needing PCIe 5.0 support (within the consumer market) is the SSD market, which is quickly reaching the limits of the PCIe 4.0 x4 interface of M.2 slots. 7,000 MB/s+ SSDs are pushing towards the limits of PCIe 4.0, and that factor alone will create the need for PCIe 5.0 over the next few years. As it stands, Alder Lake's PCIe 5.0 support is not useful, and Intel needs to find a way to justify its use of PCIe 5.0 if they want it to be an important marketing point for Alder Lake.
Right now, it looks like Intel added PCIe 5.0 to Alder Lake for marketing reasons, not technical reasons. As it stands, PCIe 5.0 support is a useless feature for consumers. While PCIe 5.0 devices will eventually come to market, Alder Lake doesn't offer enough PCIe 5.0 lanes to support a meaningful number of PCIe 5.0 devices.
You can join the discussion on Intel's Z690 motherboard platform and Alder Lake on the OC3D Forums.