Computers and heat density

Tim Shoppa shoppa_classiccmp at
Sun Aug 13 08:55:47 CDT 2006

Recent posts on the subject of "modern" logic families and PCB's
make me think of an obvious trend in computing over the past
several decades:

Power density (and required cooling/heat dissipation) have grown

A desktop PC of 20 years ago often had no fan, or if it had one
it was just to generally keep air moving through the case and not
to cool any specific heat producing sections.

Of course modern desktop PC's (since at least the early/mid 90's) have
vastly greater heat production and cooling requirements, with CPU heat
sinks and fans being vital to reliability.

At the same time, and a subject of increasing frustration for me,
the number of computers required to do a given task has gone up
exponentially. Tasks that used to (meaning 20 or 30 years ago) used
to require a single PDP-8 or PDP-11 class minicomputer now use dozens
to hundreds of PC-clone's to do the same functions. The heat production
(and power and cooling requirements) of all the resulting PC-clones is
hugely higher.

In fact through the recent heat wave, computer/server usage is mentioned
as a sizable component of total power consumption on the grid, when
presumably 20 or 30 years ago it was negligible.

I personally see massive government/military contractor computer
projects turn into a race to buy the fastest/biggest/best/most computers
with little regard as to whether you need hundreds of blade servers
to run a single web site or mail server. It is also frustrating
to see Peoplesoft/Oracle/Microsoft sell thousands and thousands
of licenses at a cost of hundreds of millions of dollars when the
same function used to be done by a single PDP-11 with a couple of

Yet nobody seems to be asking: WHY DOES IT TAKE 100 COMPUTERS TO DO WHAT
A SINGLE COMPUTER USED TO DO? After all, computers today are hundreds
of times more powerful (CPU-wise) than they used to be. Disk storage
is vastly more compact power efficient than it used to be.

Don't get me wrong, I'm not sure everyone should have the same
appreciation that those of us reading this message for "that computer
of 30 years ago is good enough for what I do". Yet I would expect
that any real demand for actual computer utility would make some
sort of progress other than "buy ten thousand seats of Oracle licenses
and several hundred oracle servers just to serve the needs of a single
municipal city government HR and payroll".

Some random articles about building sites where the required power/
cooling density is either explicitly addressed or in retorspect they
didn't have enough:

  NSA risking electrical overload (Baltimore Sun):,0,5137448.story?coll=bal-home-headlines

  Google's Server Farm with massive cooling towers:

OK, diatribe mode off. I'm going back to my 6SN7's and 807's playing
some old 78's I got at the thrift store yesterday.


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