# Python, <s>358</s> <s>281</s> <s>268</s> 221 bytes
Monochrome is *so* last year. This uses multiple processes and syscalls to achieve **two color** CPU graphs!
from time import*
import os
A='%-99o'%int('t12q2lxqkap48euoej9429cstbnazg84zyxflqzi8k1',36)
f=open('/dev/urandom')
for i in'0123456':
t=os.fork()
while t<1:T=int(time())%50;(sleep,(id,f.readlines)[i<A[T+49]])[i<A[T]](1)
Output from Activity Monitor (OS X 10.9):
> 
> 
>
> 
Output from MenuMeters:
> 
All outputs were generated with an update speed of 1s. No significant background tasks were running, though this output quite easily beats out any single-threaded CPU task.
This code assumes you have 8 cores. It should be pretty easy to modify for fewer/more. It is *portable* to Linux/UNIX systems (though it has only been tested on OS X), and should produce the same two-color output for any CPU monitor that can distinguish User from System CPU time.
Essentially, this works by forking off seven processes, each of which will choose to spend 1 second sleeping, spinning in usermode, or spinning the kernel. Spinning in kernel mode is achieved by requesting large globs of data from `/dev/urandom`, which forces the driver backing `/dev/urandom` to spend a lot of "system" CPU cycles.
EDITED [07/21]: Shortened significantly by using `fork()` instead of `multiprocessing.Process` (`/dev/urandom` only works on *NIX systems anyway so this doesn't reduce portability). Note however that the program now spawns *background* tasks; you may have to `killall Python` (or similar) to get rid of the CPU-eaters.
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I couldn't resist implementing a few more letters. I got 16 letters, plus a few symbols:



The complete alphabet is "ACDFHILMNOPTUVWY", with symbols "._~/\". There are probably lots more characters that can be represented.
Entirely ungolfed code for the extra letters:
from time import*
from multiprocessing import*
chars6 = {
'A': ('123456654321',
'000123321000'),
'C': ('344556666666',
'321110000000'),
'D': ('666666655443',
'000000011123'),
'F': ('66666666666666',
'00002222244444'),
'H': ('666664444466666',
'000002222200000'),
'I': ('66666',
'00000'),
'L': ('666662222222',
'000000000000'),
'M': ('6665544334455666',
'0004321001234000'),
'N': ('66665544336666',
'00003322110000'),
'O': ('3445556666555443',
'3221110000111223'),
'P': ('666666666555',
'000003333444'),
'T': ('777776666677777',
'444440000044444'),
'U': ('6666322236666',
'4211000001124'),
'V': ('66654322345666',
'33321000012333'),
'W': ('66542466424566',
'43210133101234'),
'Y': ('66665433456666',
'44333000033344'),
'_': ('1111111111',
'0000000000'),
' ': ('000',
'000'),
'.': ('12221',
'10001'),
'~': ('44445544334444',
'11223322112233'),
'/': ('2234566',
'0012344'),
'\\': ('6654322',
'4432100'),
}
s = 'ANCHOVY '
A = '000'.join(chars6[t][0] for t in s)
B = '000'.join(chars6[t][1] for t in s)
t=time()
f=open('/dev/urandom')
def F(n):
while 1:T=int(time()-t)%len(A);[sleep,[].count,lambda x:f.read(4**9)][(n<int(A[T]))+(n<int(B[T]))](1)
for i in range(7):Process(target=F,args=(i,)).start()
F(7)