[conspire] CPU upgrade questions (was sous vide question.)

[Rick Moen]

Quoting Leo P (yaconsult at gmail.com):

> They are compatible within generations.  My X58 motherboard that now has an
> I7 950 will work perfectly fine with the Xeon X5850 in it because they are
> both LGA 1366.  While the Xeons cost hundreds of dollars when they were
> current, they are now extremely cheap on the used market - $25.  What would
> be gained is two additional cores, four additional threads, and a much more
> overclockable chip that runs cooler.  I do not want to go to a more recent
> generation yet because the LGA 1366 is currently perfectly adequate for my
> needs and the system has 12 GB of fast memory in it.  This site was a good
> place to compare CPUs and motherboards to see which ones were compatible:
> http://www.pc-specs.com/pc-custom-builder/cpu

In what follows, I'm going to be guilty here once again of expostulating
on the basis of plausibility without good data, so set your skepticism
to suit local preferences.

The point about price decline over time is an excellent one, and I'd say
when this happens is probably the _only_ time it might make economic
sense to swap out a motherboard's CPU for a better/faster one.  As you
say, you can get more cores and gain overclocking possibilities.

The remaining question is how much good that's going to do you, which in
turn depends a great deal on whether your use-cases and applications of
primary concern are currently CPU-bound.  So, for example, if you do
CADD, or chip design, or molecular modeling, or A/V, or gaming, that is 
more likely to substantially benefit than if, say, you do Internet
serving, or databases, or many other sorts of common things that end up
being RAM-bound or I/O-bound.

For most things *I* do with Linux, the machines I do them on end up
being RAM-bound or I/O-bound.[1]  And when I say RAM-bound, don't forget
that the _generation_ of RAM can matter quite a bit, being vital to how
fast fetches end up being.  Which in turn underlines why upgrading from
one CPU to a better one _might_ not translate into as much real-world
benefit as you imagined -- depending.  In some cases, it might be wiser
to just tuck that CPU-upgrade money into the fund towards a newer
motherboard + CPU + faster storage + spanking-new DDR4 RAM.

OTOH, by the time the price drops to $25?  Sure, why not burn a Jackson
and a Lincoln to see what happens?  ;->


[1] Which general pattern I attribute to PeeCee equipment generally
being overendowed with CPU grunt in order to compensate for Microsoft
Windows being a CPU hog, whereas Linux is not.  Note that I picked 
up my recent Zotac mini-PC purchase, intended for use as a home
network-infrastructure server, in part because I liked its 4-year-old,
2-core 'Haswell' Celeron 2961Y _not_ being overpowered, hence low-power
and low-heat.