Overall, "the cost and performance advantages originally anticipated for ARM [servers] are problematic, given the way things unfolded for ARM and the x86," Norrod said. His company currently ships low-power servers using Intel's Atom-based Centerton and Avoton SoCs.
Dell built prototype 32-bit ARM servers using SoCs from Marvell and the startup Calxeda. However, Calxeda went out of business, and Marvell has been mum on any plans for a 64-bit chip.
Separately, multiple sources have said Samsung has canceled plans for an ARM server SoC. Reports say Nvidia has canceled or at least delayed plans for server SoCs using its new Denver 64-bit ARM core, which will be used first in mobile chips.
At Hot Chips, Applied Micro said it is shipping its first-generation X-Gene, the first 64-bit ARM server SoC to hit the market. However, it did not say who is using it in systems.
Applied Micro "used to tout they would have time-to-market advantage, but I think that's gone at this point," said Nathan Brookwood, principal of the market watcher Insight64. "At least they are shipping a standard product instead of just sampling it, which they have done for 18 months."
Also at Hot Chips, AMD described its Seattle ARM server SoC, which is expected to be in production this year and may be the second 64-bit ARM server SoC to hit production.
AMD, Broadcom, and Cavium have all announced high-end plans this year for ARM server SoCs using custom out-of-order processors. Cavium's chip are expected to ship in 2015, but AMD's chips will come later. Broadcom has not provided a timeframe for its SoCs.
"At the apex, I think there were 14 ARM server SoCs planned," Norrod said. "My current count is there are now nine. The market is not large enough," and the use cases for ARM servers remain unclear.
There's a relatively small set of use cases where the software lift is low enough to see how it comes to market. It may be a narrowly defined market with fierce competition that will not disrupt the rest of the [server] market.
There are a couple options. The hyperscale [data centers] who control their own software destiny [could use ARM servers], pieces of Amazon and Microsoft, but not public cloud. Maybe they will be used as appliances, maybe even LAMP [Linux, Apache, MySQL, Python] appliances as web front ends.
ARM is the first CPU architecture to come along and get significant market share against the x86 in a long time, but it's a very complicated situation, and it's unclear how it will come out. I'm smart enough to know I can't predict it.
— Rick Merritt, Silicon Valley Bureau Chief, EE Times