Intel's Upcoming LGA 1851 Socket Details Revealed

Intel's LGA 1851 socket is waiting in the wings to replace LGA 1700, used on both Alder and Raptor Lake platforms. It'll get a new lease on life soon with the upcoming Raptor Lake refresh, but its successor will arrive in 2024 for the company's 15th Generation CPU lineup code-named Arrow Lake. Yesterday the hardware testing site Igor's Lab shared some internal Intel data about its theoretical performance, and today the site is divulging engineering details on the socket itself. The big changes come in two categories; I/O options for PCI Express and how the CPU is mounted.

It's been known for a long time that LGA 1851 was coming, and as its name indicates, it will include 151 more contact pins than the existing design. Despite the extra pins, it has the exact same dimensions as its predecessor and will look identical to the naked eye. It'll be introduced to the market alongside an all-new 800-series chipset in 2024, assuming Intel hits its execution targets. Like its predecessors, it'll feature an elongated, rectangular design that requires users to abandon the "dot in the middle" thermal paste approach from the days of yore.

The most significant change for LGA 1851, according to Igor, is Intel will be finally bringing its platform into modern times and preparing it for the future by making it fully compatible with PCIe 5.0 devices. It'll do this to future-proof its platform and catch up to AMD, which has already taken this action with its current AM5 socket. Intel's LGA 1700 platform only offers a PCIe 4.0 x4 connection for SSDs. If you were to drop in a Gen 5 SSD, it would have to borrow eight lanes from the GPU, which are also PCIe 4.0, by the way.

To remedy this, Intel will offer a dedicated PCIe 5.0 x4 connection for an M.2 SSD and a PCIe 4.0 x4 interface for a secondary drive. This should be enough for most folks requiring only one super-fast drive for their OS. However, despite the advancement by Intel, it's still not equivalent to AMD's offering for AM5, which has support for two Gen 5 SSDs with an x4 connection.

In addition, the GPU will get a full PCIe 5.0 x16 interface, a big upgrade from the current PCIe 4.0 design and matching what AM5 offers. This is even though no current GPU is designed with a Gen 5 connector, as both Nvidia and AMD still use PCIe 4.0. However, that's expected to change when both companies launch their next-generation architectures in the coming years. We think Nvidia will launch Blackwell in 2025, but it's unknown when RDNA 4 will arrive, though we assume it'll be in 2024. Arrow Lake will also only support DDR5 memory, the same as AMD's newest platform.

Aside from I/O changes, Intel is also changing the pressure required by the CPU's mounting mechanism. According to the spec sheets, the maximum necessary dynamic pressure will increase from 489.5 N to 923 N. This means that although existing coolers would technically fit just fine on an Arrow Lake CPU, a new mounting mechanism will be required that can apply that additional pressure. It seems unlikely that cooler manufacturers would bother to ship a mounting mechanism to people who own their current CPU coolers. Still, it's theoretically possible, so we'll have to wait and see how that unfolds.

Otherwise, Igor's article offers loads of engineering details about the new socket without any additional context, so if you like to examine technical documents, it'll be right up your alley. The new socket is expected to launch with Arrow Lake in 2024, but that's not guaranteed to happen. One of the biggest questions arising from these new details is whether or not Intel has resolved the issue of sockets getting warped due to uneven pressure being applied. This affected both Alder and Raptor Lake platforms, but never on a scale large enough to officially be acknowledged as an actual problem. This led to the development of "contact frames" that replaced the loading mechanism for the socket itself, though for its part, Intel says the warping was all within spec and nothing to worry about.