The original Athlon was bus-compatible with DEC Alpha chips - some logic boards could take either with a firmware upgrade.
Also, there have been FPGA's that slot into Opteron logic boards (Celoxica made one around 2006), and various other chips that connect directly to the hypertransport bus as accelerators.
It remains to be seen what they'll do with this. Will it be a Xeon Phi competitor (lots of cores, high thermal footprint) or something aimed at lower end uses.
What's notable about Nvidia's Tesla offerings is that they sit as a separate 1-2U rack on top of the compute box. The space and power costs of operating Nvidia GPGPUs in a datacenter are nontrivial.
If AMD ships a solid ARM product with some good on-die GPGPU components, that might compete with Nvidia, but otherwise the two are in different spaces even within the server world.
Not so sure about that.
The difference between x86 and ARM on the power/performance curve is almost purely due to design choices and trade offs. So why not create a new low-power x86 core instead of a new ARM core?
The only way this makes sense to me is for this to be a stepping stone into the mobile market. The mobile market is definitely stepping up the power/performance curve, and AMD's experience with GPUs may be a distinct advantage for them in the mobile market in the future.
So it's just a coincidence that ARM powers 95%+ of smartphones? I think not.
Given Intel's advantage in fabs and process technology I think it's all the more striking that to date they have failed at developing chips to effectively compete with ARM in the mobile market.
x86 is an ugly and inefficient ISA compared to ARM but it didn't matter as long as users plugged their computers into the wall.
ARM designs have been optimized for low power. x86 designs have been optimized for high speed. It has little to do with the architecture and lots to do with the design.
Nobody has ever tried to design a sub 1 watt x86 design. Nobody has ever tried to design a 100 watt ARM.
Only very recently have we had anything that's close to comparable. Medfield has a similar power rating to high performance ARM designs, and similar performance.
In any case, the more pressing problem for Intel is that in the mobile space consumers don't know or care what types of chips are in their phones so even if Intel could design an x86 chip competitive with ARM, consumers are unwilling to pay a brand premium for Intel that they're used to getting in the desktop market.
Of course, it's a single-core processor as opposed to the double or quad core ARM processors that it's up against, but the point is that they're getting quite close.
Transmeta tried and succeeded.
However, Intel found out that the power/performance tradeoffs for the original Atom were not what the market wanted and they've continued to evolve the design. Today there is the "Medfield" Atom system-on-a-chip which is already making its way into smartphones and already giving ARM a run for its money. Given Intel's history and their initial level of success with this first generation SoC design it's definitely far too soon to write off Atom and bask in ARM triumphalism.
Edit: It seems the announcement from AMD is in response to this announcement from Nvidia, the 2014 date also matches: http://www.xbitlabs.com/news/cpu/display/20120921010327_Nvid...
I think they confused the market, severs, with the technology they actually have - x86.
Their biggest asset is the existing infrastructure and people to build x86 - there are 2 companies that can do this: Intel and AMD.
I think there are some interesting possibilities, especially with the bursty nature of web traffic but there is also still a noticeable performance gap between ARM and x86.
Also, AMD is still working on leveraging its strengths from ATI, which might be useful depending on their market targeting.
Aside: I wonder if it's possible to have one processor core with an ARM instruction set, and another with x86 - obviously, reading from different [segmented] memory locations, albeit simultaneously. I just wonder, since they mention in the article the new Opteron cores are designed by ARM, but the rest of the processor indeed will follow AMD's design.