Originally Posted by auricgoldfinger
And if I were? I know what's prudent, but what kind of figures would be pushing it and what would be completely out of the question? Does raising the DRAM voltage even help much or is it more about the qpi?
Additionally if the stick is advertised as 2000 mhz (it isn't, it's 1600) would that in any way relate to what voltage I can get away with?
Depends on the ram and its tolerance for more voltage. Use what you are comfortable with for your overclock. Don't be afraid of a little
more voltage though, its keeping your QPI/VTT and vdimm in a .5v range that you have to be aware of.
Increasing DRAM voltage helps for trying to get your memoc to run / run stabilly above its rated spec.
The QPI/VTT is different, it involves your CPU's IMC's Uncore. On the 920 for example, the NB Frequency is required to run at 2x your ram speed. For 2000Mhz of ram this is 4000ghz uncore/nb frequency.
This is stress for the IMC, and as a result, needs more QPI/VTT to stabilize. Some chips need lots of QPI/VTT to stabilize, more then what most people are comfortable with. So yeah, QPI/VTT is important, but its used for trying to get your IMC to run at a higher speed stably without crapping out, rather then trying to get your ram to run at timings/frequencies that are out of its spec, in that situation, more vDIMM is required.
You should have a good idea of what your i7 can do in terms of QPI/VTT and uncore.
high overclock on your ram == more dram voltage
IMC stabillity > QPI/VTT.
- advertised voltage > the voltage the manufacturer tested their ram's speed and timings to run stably at.
- voltage tolerance varies really, so do what your comfortable with.
- qpi is more about stabilizing your uncore to support your rams speed rather then stabilizing your ram's overclock or trying to make it run above spec( even though a low qpi/vtt for too much uncore can result in instability ).
Tighter Timings / Faster Frequencies > DRAM Voltage. Edited by dTT05 - 2/10/11 at 2:58pm