So I ordered an iMac late 2013 maxed out ( 1TB Flash, core i7 and 780M ) except for RAM. And now that I'm waiting for delivery, I spent 4 nights in row trying to check for RAM compatibily but I literally couldn't find anyone trying the CL9 @ 1.35V. I've ordered the KHX16LS9P1K2/16 x2 ( 32 GB) for $406( Tax included ) : Kingston Technology HyperX Lovo16 GB Kit (2x8 GB) 1600MHz DDR3 PC3-12800 Non-ECC CL9 SODIMM 1.35V. Technical details : PnP JEDEC TIMING PARAMETERS: • DDR3-1600 CL9-9-9 @1.35V or 1.5V • DDR3-1333 CL8-8-8 @1.35V or 1.5V • DDR3-1066 CL6-6-6 @1.35V or 1.5V Programmable CAS Latency: 11, 10, 9, 8, 7, 6 Row Cycle Time (tRCmin) 48.125ns (min.) Refresh to Active/Refresh 260ns (min.) Command Time (tRFCmin) Row Active Time (tRASmin) 33.75ns (min.) ================================================ Ironically, Apple doesn't mention anything about voltage compatibility nor CL on their website. Although CL9 will not be noticeably faster than CL11 for the average joe, but I run intensive, resource demanding applications ( 3 hours for each task minimum with file output > 10 GB ) So saving few minutes is welcomed. From the informations I gathered I could confirm that : - 2012 Macs can take CL9 @ 1600MHZ but @1.5V - 2013 Haswell models are not stable with DIMMs @1.5V - overheat/crash - 2013 Haswell models run smoothly @ 1.35v but with CL11 and some CL10 - 2013 Haswell models can run 1866MHz RAM @ 1.35V with no issue - CL11 / CL10 There has been reports related to kernel panic and system crash with CL9 @1.5V with Haswell CPUs however, none mentioned if it was due to the higher volatege or the lower latency. The fastest RAM stick I could find was the HyperX Lovo KHX16LS9P1K2/16. I find no reason why this should not work out of the box but I still have doubts and need some opinions here. I still have till Monday to cancel my order. Thanks.