hmm
pretty confused at the moment.
i ran a test on my brand new (literally hours old) i7 stock imac on a 720p rip of stargate universe (episode 3). here are my results.
32-bit
- ~750% CPU usage.
- no other processes used > 5%
- ~210MB Real RAM
- Read/Write to HDD 4MB/s / 1.5MB/s
- CPU ~68°C, CPU fan on ~1500.
- 5 mins later hit ~2000 to keep at ~70°C. HDD + CPU fan hit ~2000 each and bring CPU temps down to ~63°C HDD at 57°C constantly
Problems:
- Finder quit and reopened? did not seem to effect computing
- annoying MDS process game in 15minutes into test and continued until conversion finished, 20-50% CPU usage entire time.
- Once finished, i tried to play the file. the audio was cutting in and out roughly every 0.5seconds. annoying
timer stopped when handbrake reached 100.00%. avg. recorded as well.
time: 24mins 59 secs
file size: 3.26GB
avg FPS: 40.33
64-bit
- ~550-600% CPU usage.
- similar results to 32-bit, temperatres/fans were not as high. computer responded a lot better.
Problems:
- None! no MDS (because no large file size). fans didnt spin up completely, computer responded very nicely.
time: 22mins 12 secs
file size: 668.7MB
avg FPS: 45.83
end result: i have provided a screen shot, they are in PNG format so clearly compressed but i think that the 64-bit handbrake is more superior to the 32-bit version (i focused my attention on the reflection coming off the glass bottle, that seemed to show the differences nicely).
file size is a MASSIVE issue with the old HB! WTF is going on there!? i chose both

TV for both conversions, very confusing.
anyway, i hope that i can help a few people out.
the first image attached is 32-bit, second image is 64-bit.