Magic and computers don’t get along
There certainly is. As with that other famous wizarding school, magic tends not to agree with delicate electronic equipment. It’s not only computers that Brakebills lacks, but (as you note), other modern technology:
The P.A. lab was transformed for the occasion. All the cabinets were
open, and every inch of the counters and tabletops was crammed with
old instruments made of wood and silver and etched brass and worked
glass. There were calipers and bulbs and beakers and clockwork and
scales and magnifying glasses and dusty glass bulbs full of wobbling
mercury and other less easily identifiable substances. Brakebills was
largely dependent on Victorian-era technology. It wasn’t an
affectation, or not entirely; electronics, Quentin was told, behaved
unpredictably in the presence of sorcery.
Of course, this very much depends on the scale of the magic. Obviously, the mere presence of single magical practitioner will not destroy sensitive electronics, as is the case (for example) in The Dresden Files. We see, for example, that magical practitioners can download spells off the Internet, without causing their computers to explode:
As it turned out, they didn’t know the rainbow spell, so she printed
out the scan she’d downloaded from the Internet that one time, it was
already two years ago now, and brought it in.
The Magician King
Brakebills is quite a different matter, though. There’s the residue of all kinds of spells:
Hamish initiated him into some of the deeper mysteries of the
Brakebills campus. What was really surprising was how much of the
stuff that the undergraduates whispered about after hours was actually
true. That blank stretch of wall, for example, where there ought to
have been a room, and the plaster was a shade lighter—that really
wasn’t an air shaft. Back in the 1950s some students had set up a
cubic thermal field in their room, possibly to keep beer cold, but
having already consumed some of the beer they inverted a couple of
glyphs, which had the unexpected effect of driving the temperature
inside down very close to absolute zero. The resulting field was so
stable that nobody could figure out a way to dispel it.
It was perfectly harmless unless you walked into it, in which case
you’d be dead before you knew it. One of the kids who cast it lost a
hand that way, or so it was said. Eventually the faculty just shrugged
their shoulders and walled it off. Supposedly the lost, frozen hand
was still in there.
Likewise, it was true: the clock was powered by a gear made of metal
reclaimed from the body of the Silver Golem of Białystok. It was also
true that there was a childishly humorous anagram for Brakebills, that
it was Biker Balls, and that the chalkboards would squeak painfully if
you tried to write it on them. It was true that ivy wouldn’t grow on
that one bare patch of wall behind the kitchens because one of the
stones had been violently cursed in a really ugly incident involving a
student who’d slipped through the admissions protocols meant to screen
out sociopaths and other people mentally unfit to handle magic. On
humid days it sweated acid.
The Magician’s Land
Look at how many basically permanent spells are described here: spells on the chalkboards, spells on the wall, lethal thermal fields, and so forth. And then there is, of course, the camouflage spell, which affects the whole school, and presumably is always on:
Being an illusionist at Brakebills was, if Plum said it herself, a
pretty sweet deal. You got to hang out in a tiny invisible folly
castle on the edge of the forest that was quite difficult to find
unless you had an illusionist-type discipline.
The Magician’s Land
And of course, there will be magicians performing sorcery around the clock.
Then, too, if the mere presence of magicians, and not merely their spells, affects electronics, it’s easy to see why Brakebills, with many magicians all in one small space, might experience far more difficulty than a single hedge witch. I can’t find anything to indicate whether this is the case, but it’s a definite possibility.