Can a motherboard that supports multiple CPUs run with fewer CPUs than it supports?

Question

I'm looking at building out a pretty beefy server, and I was wondering if I were to get a motherboard that supports multiple CPUs such as this one, can it run with only one or two CPUs temporarily?

I'm thinking it would be perfect if I could put off buying two or three processors for a couple of months to save money, since at first they won't be necessary.

Is this possible, or does it have to have all four processors in place to run?

Thanks

Solution 1

Yes :) you don't have to plug the two processors. I have the Tyan i5400xt (Xeon Harpertown) and I simply plugged the first processor for months. You don't have anything to do, the bios will see that there is only one cpu.

Solution 2

Sure it can. My suggestion is: Don't do it. Fill it up to the limit right away.

My argument is that in general these kinds of system REQUIRE all CPUs to be 100% identical. If you wait a month too long you may very well run into the required additional CPUs no longer being available.... of being very expensive.

Solution 3

Only desktop Intel/AMD stuff. On other CPU systems like Itanium you need dummy voltage regulartor modules that are put into the CPU socket.

I once (around 2003) bought a MP Board for AMD and plugged in only one CPU. Thought spend 200 Euro more and therefore have a later option (when CPU's are cheaper and my business is going) i can get double speed upgrade. Didn't work at these days as the CPU was quickly out of sale and no way to mix CPUs with different speeds.

I learned from this. Never do to provide yourself with an upgrade path. Buy now and sell it after upgrade - this saves much more money in the end.

Solution 4

I have 2 HP servers here with 2 CPU socket available and running with only one CPU for 3 years now and there's nothing wrong about doing that plus it give you the possibility to add another CPU if needed at lower cost later ;)

Solution 5

Or what about using all dual core cpu, and then if needed, upgrade to quad? One virtue to that is more memory bandwidth, at the cost of having your memory fragmented (each socket has it's own memory bus and sockets) and perhaps needing to replace memory in the future.

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Comments

[user234702]

Be carefull, I don't know if it's still true, but you used to have to buy a special socket insert to place on the non-used socket on some motherboards.

[Razique]

Not on Tyan Motherboards actually, but yah, some mobo require that you disable the second socket otherwise the server won't boot up. Regarding this special socket insert I never heard of it, but yah that's not impossible (a bit weird though) that while the insert touches certain pins, the signal will be interpreted as the second socket deactivation I guess

[inari6]

Don't forget to account for the Memory capacity / fill pattern being different if you don't have all of the CPUs installed for certain setups.

[Ernie]

Also, there's the "temporary fix" mentality which must be avoided. If growth is enough to predictably need the extra CPUs in the future, get them now. The problem with server upgrades is that they require downtime.

[Chris B]

Yes of course ;)

[Max Schmeling]

Short spurts of downtime isn't really an issue in this environment as long as it's scheduled. Cost, however, is an issue. It's a company that is almost gauranteed to grow very quickly, but intial capitol is very low (don't want to spend all of the investors money on IT stuff). Believe me, I hate the "temporary fix mentality" more than just about anyone.

[Niels Basjes]

@Kronick: I have a (very old) Pentium II 300 MHZ Dual CPU system here. That system came with a 'blank cpu card' that should be used when only 1 CPU was installed. I never used it though.

[STW]

+1, matching processors is important since slightly different revisions may have slighly different behaviors / bugs--whenever I've torn apart a professionally built multicore system the processors have sequential serial numbers.

[Ian Clelland]

The special insert was typically a bus terminator -- I remember that it was required on Intel Slot 1 (Pentium II, Pentium III) motherboards. You could get some motherboards to boot without the terminator installed, but you'd end up with stability issues.

[Lothar]

Hmm if the small money for a second CPU is a financial problem then you have a more serious problem. I guess the Investor is FFF (Family, Friends, Fools). And i don't like this grows very quickly. Growth at the beginning is always infinite. Going from making 0 money and then earning $1 is infinite growth. Yes the second step is harder.

[Rowan Hawkins]

The special socket insert was something that happened with much older generation systems. Those systems usually had separate voltage regulator modules which needed to be installed to activate the processor socket or slot. I'm not aware of any Xeon system that needs such a configuration.