THE CRUNCH
Intel's Xeon 6+ "Clearwater Forest" server chips, the first server parts built on the company's 18A process, have been shipping for just over a quarter, and they are now reaching vendors beyond the hyperscalers that got first dibs on supply. ServeTheHome has run the numbers on the resulting question: which of the four SKUs, spanning 144 to 288 cores and roughly $5,000 to $15,000, makes sense for which workload. The short answer is that Intel has kept the stack unusually simple, with no features gated behind specific chips, so the real decisions come down to core count, power and cache.
ServeTheHome's review of the stack highlights a useful wrinkle: the top two chips, the 6990E+ and 6980E+, support Intel's Speed Select Technology, which lets each run at one of two TDPs. Higher TDP modes buy higher guaranteed base clocks and all-core turbo speeds; lower TDPs run cooler and closer to the chip's ideal point on the power/frequency curve. The flagship 288-core 6990E+ tops out at 2.8GHz all-core turbo in its 450W high-TDP mode, while the low-TDP mode drops turbo by 14% to 2.4GHz and cuts the TDP by 120W to 330W.
That low-TDP mode is where the efficiency story lives. With every SKU in the family rated at 300W or more, the high-core-count chips in their low-TDP modes offer the best watts-per-core figures. On a watts-per-core basis, ServeTheHome calculates the low-TDP 6990E+ at 1.15W per core and the 6980E+ at 1.14W per core, against a 192-core AMD EPYC 9965 at 2.34W to 2.60W per core, though it cautions that AMD's Zen 5 core is a P-core with two threads per core, so the figures land in a similar ballpark if you count threads rather than cores.
Smaller chips trade throughput for speed and cache. The 144-core 6960E+ guarantees a 2.4GHz base clock with a 3.0GHz all-core turbo at 330W, roughly 25% higher clocks than the flagship at the same TDP, making it ServeTheHome's sweet spot for workloads that need many cores but cannot scale to 288. It is also the cache pick: because L3 does not shrink one-to-one with core count, the 6960E+ carries 3MB of L3 per core, up from 2.5MB on the 6970E+ and 2MB on the 6990E+.