That statement in Asus manual has long been overturned by Bit-tech's article and Anandtech.com article and info they received from intel themselves read http://i4memory.com/wp/article/327 and http://i4memory.com/wp/article/191
The correct statement should be
"Vdimm >1.65v is safe as long as vdimm is within 0.5v of uncore voltage"
DFI CPU VTT = Uncore volts
Asus QPI/DRAM = Uncore volts
Default DFI CPU VTT = 1.21v which i think is similar to Asus ?? So now you know why Asus put >1.65v vdimm warning label there. As folks who aren't aware of the uncore to vdimm 0.5v requirement, will try to keep CPU VTT at default values and raise vdimm beyond 1.65v. This will cause vdimm to uncore voltage to move out of bounds from 0.5v requirement and thus cause damage to CPU.
To keep CPU safe, VDIMM must keep to 0.5v within Uncore. DFI UT X58-T3EH8 bios does this automatically for you - see point #16 for DRAM Safety for my DFI thread at http://i4memory.com/102537-post3.html
Max intel spec'd uncore/CPU VTT is 1.35v and default uncore is 1.1v (but most X58 boards set 1.2v) so basically you have vdimm range of 1.6-1.85v vdimm to be comfortable within CPU safe parameters.
But folks are benching CPU VTT/Uncore to 1.5-1.6v to get >DDR3-1866 speeds. For example Corsair DDR3-1866 modules are validated at CPU VTT /uncore of 1.5+v.
Now to be 100% safe, measure your vdimm and uncore volts using multimeter for your board so you can precisely know the distance between vdimm and uncore volts.
For DFI UT X58-T3EH8 i did those measurements at http://i4memory.com/f80/dfi-ut-x58-t...results-14011/ using DFI's provided DMM measure pads
Right now testing Asus P6T6 WS Revolution as well but monitoring in bios and windows don't report cpu vtt so hard to get an exact value but so far so good http://i4memory.com/showthread.php?t=18752
Older DDR3 with higher rated voltages will work just to keep within 1.65v vdimm, you'd probably have to underclock memory or loosen timings.






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