From the outside looking in, Intel's desktop CPU roadmap has been a bit murky for the past year or so. We have confirmation that Intel's 14th generation Raptor Lake refresh will arrive in October; Meteor Lake was initially expected to replace Arrow Lake, but that was cancelled; and the new Raptor Lake will be the first of Intel's new CPUs to arrive in 2024.

Whichever Lake arrives in 2024, a new LGA1851 socket will undoubtedly replace the nearly two-year-old LGA1700 socket on current 600 and 700 series motherboards.

Igor's lab is on a roll: following up on his Arrow Lake performance prediction, Igor has now revealed a treasure trove of information about the LGA1851 socket, which is not only for Arrow Lake processors, but certainly for the generation beyond. The LGA1851 socket will be the first of Intel's 800 series chipset motherboards and will probably debut in the form of the Z890.

As the name suggests, LGA1851 has 151 more pins than the current LGA1700 socket. The additional pins are primarily intended to improve support for PCIe 5.0 SSDs. This means that 800 series boards will simultaneously support full-bandwidth PCIe 5.0 x16 slots for graphics cards and PCIe 5.0 x4 NVMe SSDs; the CPU should also support directly attached secondary PCIe 4.0 x4 SSDs.

This is roughly consistent with AM5 motherboards with Extreme chipsets; for AMD, secondary PCIe drives will also work at PCIe 5.0 speeds, albeit in a x8/x4/x4 configuration. Current LGA1700 boards support PCIe 5.0 drives, which means they share bandwidth with the primary x16 slot even when only one drive is installed; LGA1851 is a definite improvement in this regard.

Now let's talk about socket dimensions and what they mean for current CPU coolers. The good news is that the X, Y, and Z dimensions are the same, and therefore the motherboard mounting holes are likely to be the same as well. However, the maximum dynamic pressure has almost doubled from 489.5N to 923N. This means that an LGA1851 CPU requires more downward pressure on the CPU cooler. This means that many coolers require LGA1851-specific mounting kits.

Another interesting note: Igor's Labs has faced some issues with LGA1700 CPU warping, but noted that inquiries about transient bending strain should be directed to local engineers. This refers to socket makers like Lotes and Foxconn. Although the mechanism appears to be much the same as today, manufacturers will certainly implement a fine-tuned mounting mechanism. This should eliminate the problem of warpage, which could be exacerbated by increased downward pressure.

It is a little disappointing that there are no retention clips on either side of the CPU, as in the LGA2066 mechanism. Personally, I am a big fan of AMD's Threadripper mounting mechanism, but this requires an additional hex driver, and for cost reasons, I doubt it will ever be implemented on a cheap B810 or B860 motherboard.

While the LGA1700 and LGA1851 sockets are similar in appearance and dimensions, they are essentially quite different in terms of CPU compatibility and perhaps cooler compatibility.

Upgrading comes at a significant cost: DDR4 support is being discontinued, so a new Arrow Lake CPU may require a new motherboard, DDR5 memory, and possibly a new cooler (or at least a mounting kit) as well. AMD buyers were hurt by similar requirements when the AM5 platform was launched. Although cooler support was carried over from AM4, buyers suffered from the terrible pricing of DDR5 memory at the time.

Assuming Intel sticks with its trend of maintaining socket support for two generations, the good news is that 800 series boards with LGA1851 sockets should also support Lunar Lake CPUs. LGA1851 900 series motherboards It is not a leap to assume that LGA1851 900 series motherboards will support Lunar Lake. Start saving, although the AI may kill you by then anyway.