In this thread:
http://www.xtremesystems.org/forums/...77&postcount=1
Tony explains that choosing the higher 1333 FSB strap might lead to
higher clocks, but that latency is pessimized. I had previously
observed that memory performance stuffers


Here are some real numbers. Basically it compares a E6600 at 1333 *
120% = 3660 MHz to the same setup at 1066 * 150% = 3600 MHz. The
memory in question is the Supertalent DDR2-1000. I had to take it to
800 MHz with the 1066 strap but as you see even then it comes out
faster.

Results (short ones best of three):
Code:
                                Conroe  1066*1.50       idx1    idx2
FC5/amd64:                      1333*1.20      Opt175@2.6
---------------------------------------------------------------------------
stream MB/sec                 3951    4411     2469     1.116   0.62
drystones Mio                 16.7    16.5     7.5      0.988   0.45
superpi 1 M sec               10.6    10.5     26.4     0.991   2.49
superpi 4 M sec               -1      58.1     141.3
superpi 32 M sec              824     782      1755     0.949   2.13
dual superpi 32 M sec avg     1066    1007     2000     0.945   1.88
Linux -j 32 real              487     459      713      0.943   1.46
Linux -j 32 cpu               868     853      1395     0.983   1.61
Watts idle                    178     180(175) 120      1.011   0.67
Watts Linux -j 32             247     251(243) 217      1.016   0.88
Watts dprime 5 min            279     285(275) 230      1.022   0.82
FreeBSD 32 bits make world    1114    1126     1749     1.011   1.57
Linux -j 32 real (in FB)      132     133      202      1.008   1.53
Linux -j 32 cpu (in FB)       247     244      390      0.988   1.58
"idx1" and "idx2" are the relative values of the 1066*1.50 run and the
Opteron run against the 1333*1.20 run.

Watts in (...) were at 1.450 V, real run at 1.475 V. Note that both
Conroe runs are at 1.475 Vcore and that the 1066*1.50 has lower Vdimm
but higher Vmch. Watts for Conroe include waterpump which takes about
20 watts, Opteron is on Freezer 64 Pro. Conroe has 2x 1 GB,
Opteron939 has 4x 1 GB ECC.

The latter Linux kernel in FB tests are building a small 32bit Linux
kernel using a 32 bit Linux compiler in the FreeBSD Linux compat
environment.

As you can see, this 32 bit environment, even in the Linux layer of
FreeBSD, reacts precisely to the CPU in use like the Linux native 64
bits. This rules out that somehow magically Conroe is weak at 64 bits
and it also rules out that somehow FreeBSD's Linux emulator is somehow
magically screwing something up.

However, there is tendency that the 1066*1.50 run, which has lower
clockspeed but higher memory bandwidth, on average likes the 64 bit
code more. Hardly surprising and the difference is too small to make
a fuss out of it.

I'll followup with the exact settings in a minute.