I read liquid metal mustn't be used on aluminium, it corrodes it. I'd say stay well clear, you'll probably get as much temp drop with MX-3. You should read this thread, it's very interesting, and will put a few people off no doubt.
And here is an interesting quote from the last page of the thread:
http://www.xtremesystems.org/forums/showthread.php?t=72814
"Oh dear!
Oh dear, dear, dear!
Went to swap-out the motherboard on my test rig. Heatsink would NOT budge. Tried heating, tried freezing. No joy. Tried a TINY bit extra force on the
frozen heatsink and AAAAAAAAAAAAAAAAARRRRRRRRRRRRRGH! The CPU came out of the socket. Frantically checked for broken/bent pins ... all OK. Phew!
Recap & advice.
a)
Liquid Metal gave slightly sub-standard temps but mechanically OK when applied to ONLY ONE SURFACE (heatsink or IHS).
b) Liquid Metal gave slightly sub-standard temps but mechanically BAD when applied to BOTH SURFACES (heatsink and IHS).
More, miscellaneous info:-
Once removed from the motherboard socket it took a LOT of force to part the CPU from the heatsink. Checking the IHS & copper core I found that the
Liquid Metal had taken on the consistency of Super Glue i.e., it wasn't liquid anymore and the two surfaces had hard patches of Liquid metal. I tried Brasso but had to re-lap the heatsink - also there seemed to have been a small reaction with the copper and the once-mirror surface looked - um - "wavey". Cleaning the IHS was a nightmare, as you can imagine. All in, getting rid of the Liquid Metal from the heatsink and IHS took 10 hours with every technique, material and chemical known to man. That includes a little bit of lying down to stop getting angry! And recalling how conductive Liquid Metal is, I was mindfull to be extremely careful about residues at every stage of the cleaning process. I'm not entirely convinced that I've removed all traces of this stuff from the IHS but it is now very, very shiney.
I have no clue why Liquid Metal is OK when applied to just one surface yet works so differently when applied to both mating surfaces. It's almost like it's a different compound "