Here's my spec:
Asus P7P55D-E PRO
i5-750 (non-OC, turbo enabled)
2 x 2gb Kingston hyperX DDR3 1600mhz (9-9-9-27 | 1.7-1.9V)
Since my cpu is stock setting(bus 133mhz), it auto turn dram into 1333mhz (9-9-9-24 | 1.5V)
I tried increase bus speed to 150mhz, it auto turn dram into 1500mhz and 1.7V (cas 9-10-9-24 or near like that, i forgot)
Some say dram volt need to be within 0.5v range of uncore or it will damage processor and I check in bios my uncore is around 1.1v, so 1.7-1.1=0.6
It's already >0.5 then i quickly revert to stock setting and dare not to try any further until advice given.
Is there anyway to use 1600mhz but keep the volt inside 1.65V?
If no, can I tweak the 1333mhz's cas latency?
THIS is manual of my dram, i see something like "Programmable CAS Write Latency(CWL) = 7(DDR3-1333)"
Hope I can tweak the 1333mhz if 1600 is not the option.
The max voltage you want for your ram is 1.65, any more then that can potentially damage you cpu (according to intel).
Your rams speed is calculated by the bclk x RAM multiplier (which will be 10), so if you increase the bclk to 160 then that'll give you the speed you want.
But this also increases your cpu's speed (bclk x CPU multi) so if you want to keep it at stock then you'll have to lower the multiplier.
But as you've got an ASUS you should be able to skip all of that, should be an option in the BIOS to automatically set everything to work with faster ram, read your manual to find it.
Edit: Forgot something else to warn you about, once you've done this it'll automatically disable turboboost.
The reason for this is that turboboost increases your cpu's multiplier on a single core so if it stayed enabled it could potentially increase your cpu's speed by a considerably larger amount then was originally intended (160 x 22 = 3.52ghz), which whilst not a huge overclock does mean that you'll have to keep an eye on temps + vcore. Turbo can be re-enabled in the BIOS if you wish to though.
Looks like you bought RAM that isn't entirely suitable for your board. The V range of 1.7-1.9V is greater than the max spec of 1.65V - as you've recommened. If you're comfortable going higher, you could raise the Vtt (uncore) to 1.2.
I agree with above, if you want to raise the frequency, set the DIMM V manually to 1.65V. Then start your OC and see what you can get it stable at.
Or if you want to leave it at 1333 MHz and tighten the timings, just change the RAM settings and see what you can get it stable at. Set the DIMM V to 1.5V and try changing your RAM to 8-8-8-24.
Yeah that's what I thought earlier but I realized most i5-750 test setup review in tomshardware are using 1600mhz 1.7~1.9v dram too and not sure how they tune it, they won't answer it anyway if any leave comment there.
Is ok I will leave it auto as like nobody knows the answer.