Ask HN: Why not have n processors in one motherboard? | Hacker News Reader

Ask HN: Why not have n processors in one motherboard?

1 pointtechsin10113 comments

Sorry never took system architecture, but it has always bothered me why you can't install another processor at least upto 6, just how you can install multiple rams into motherboard.

These day processors already have cores, what it matters if they are on one chip or multiple chips.

Why can't you install 6 cpus with 6 cores each. 36 cores.

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This already exists. It's called SMP, and the cost of adding processors goes up exponentially. The processors have to be connected, with in a hub or a switched config. Hub is slow if there is lots of IPC and switch is expensive if fully connected. I don't think very many people make machines with more than 6 sockets.

Intel has 8 way systems - https://www.lenovo.com/us/en/data-center/servers/mission-cri...

Sure, and Bull sells systems with far more than that. They're always highly specialized and cost $$$

Can you post a link to such a system?

https://atos.net/en/products/enterprise-servers/x86-servers-... 16 Intel Xeon E7 v4 processor sockets + 24TB RAM.

Amazon just announced these 8-socket Intel systems: https://www.businesswire.com/news/home/20180927005961/en/AWS...

Thanks!

SGI makes machines (SGI UV series) with up to 256 sockets, but obviously not on one board, but as blades with NUMALink connections. (Still a single machine though, not a cluster)

Nice! Wish there was some way to get remote access to one of these for running some benchmarks.

If I remember right, NUMA effects are lot more pronounced, since the NUMALink connections are slower and higher latency than QPI.

i guess my question is why is it not a default thing for regular user pcs.

why do i have to buy a new cpu, why can't i buy 4 amd cpus instead of buying that i7 to get performance i need.

Because it'd be more expensive and complicated, and thus nobody would buy that stuff. Was slightly different at some points in the past, where more enthusiasts had them, but back then CPU speed was something that really mattered for consumers. + market segmentation: if you really need multiple CPUs, you likely are willing to pay for it.

you can't strap N cpus together and get the same performance as a single fast CPU unless you have problems that map well to that. It's cost effective for intel or AMD to throw multiple cores on a die, but less effective to put multiple sockets on a motherboard as the motherboard now needs a bunch of expensive traces between all the sockets to handle the communication which is required to parallelize algorithms.

It's just not cost-effective. And you can buy dual socket machines- they start around $2K which is about 4X the cost that a consumer wants to pay.

Multi-processor motherboards are a thing in workstations and servers.

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