Progress report and a few q's. I spend FIVE HOURS tonight replacing my HSF and doing the mobo mod (I am slow I guess).
1) Zalman 9500
I installed this without too much issue. I did notice that the fan is mounted slightly off axis such that a fairly small force applied to the center can flex the support enough to allow the fan blades to contact the radiator blades in one region (due to the off axis tilt). After hooking everything up I crossed my fingers and powered on to hear a loud RATATAT. Thought I was screwed, but turns out I was just stupid and had a cable touching the fan blades. The crookedness of the fan still bothers me a bit, but there is no interference now, and if it ever does make contact I'm fairly sure I could fix the problem with a washer or a small bend to the mounting hardware.
I specifically got the LED model because it has the 3-pin fan power, and even though the 4-pin (on the non-LED) was made for 775 boards, I was reading a lot of people didn't like having the fan auto controlled. I did not install the "Fanmate" knob-controller because I was hoping to find some software (like Speedfan) which I could control it with, but I'm not having any luck here. I'm guessing the fan is on full blast since it's a bit loud, which makes the next point even more disappointing:
At idle, there is only a ~6 degree drop in temps (53 to 47). At load it is more pronounced (70+ to 60)... I say 70+ because I aborted the test when it reached that value (old HSF setup). These are core temps... the "CPU temp" reported by Everest remains a good 15 lower.
From the reviews I read I was predicting I'd be able to have the fan on medium (much quieter) and still beat my old temps by 10-15 deg. Instead I'm seeing a 6-10 drop (from temps that were very high) with fan on what I think is high.
Also, I'm getting a BIOS warning about no fan attached to the 775 fan connection. Need to figure out how to disable that.
2) Mobo mod (HS covers, TIM)
Seemed to go off without a hitch. But I am only seeing a 3 degree temp drop. Before the mod I saw 56 at idle or load. Now I see 53.
The small drops on both components disappoint me. I can only guess two things (1) the paste needs to go through a few cycles and get "broken in" or (2) I didn't use enough paste. I spread it very thin as I read to do, as thin as possible without actually leaving any area uncovered. This is good, right?
Any other ideas about my small drops in temp?
Another note. My room is very hot, probably over 80 degrees F. So maybe that is somewhat responsible for my high temps. But does not help explain why I didn't see a bigger drop.