Skylake and DDR3 memory? How that works?

[Contiusa]

Hi guys, I would like to figure a question. I am sure the Skylake memory voltage has been discussed before, but I would like to know the details.

I know that it is not advised to use DDR3 1.5v or 1.65v memory because this forces the integrated memory controller. But is there a way to worthily lower the values of VCCIO and VCCSA to the recommended Skylake levels and use a DDR3 1.65v memory for example?

Would that mean that you need to lower the memory clock or (elevate) timings so much that it makes no sense on doing it or can you use a DDR3 1866Mhz at 1.65v and stock timings and at the same time set proper voltages for VCCIO and VCCSA using a Skylake processor?

Are these values that flexible? From my experience with overclock, there is always a compromise, and if Skylake uses 1.25v memory, to adjust a 1.65v memory would become a moot point and compromise the memory performance in timings or clock.

Could someone explain how that works and if there is any sense in using DDR3 and adjusting VCCIO and VCCSA? Not to mention that not all motherboards allows you to change voltage values.

I appreciate any info,
Regards,

 

[13thmonkey]

it would be highly unlikely that the memory would function at 1.35 if it was designed for 1.65.

 

[Contiusa]

Thanks, and would that be easy to lower the VCCIO and VCCSA to run safely a 1.65v memory with Skylake or it is likely of you to have instability issues?

Would that be the same as CPU overclock? You can only milk a chip to a certain degree?

 

[13thmonkey]

A good undervolt might get you from 1.65 to 1.6 and still be functional, I don't see that running at 1.35V is at all likely to happen. In the zombie apocalypse scenario where these were the last two stick of ram for a machine you absolutely had to run for a few hours, then you'll be ok, if you wanted to run for longer you could possibly run them at 1/2 their rated speed, or slower, relax the timings at lot, and you might, just might, get it working at 1.35V. But in the real world, it's not going to happen, if you want to go ahead and research it and try it, go ahead, give it a go, but I for one won't be spending any time doing it for the cost of $50-60 to get some new ram.

 

[Contiusa]

Thanks, no, I am not going to do that! It is just that a brat is questioning this stuff in a Brazilian forum (I am from Rio de Janeiro) and I am asking here to know a bit more. Especially because people are kind of buying his stuff, that it is piece of cake to make a 1.65v stick to work safely with Skylake. That it is all a myth and that kind of thing. Then I come here, in international forums because I know that people are playing with overclock and voltages since forever.

 

[13thmonkey]

They can but try it, it'll work or it won't, but it'll be fairly safe. I would wipe any OS that I installed like that though.

 

[Contiusa]

it'll work or it won't

You mean that it will depend on the quality of the memory stick to handle lower values? From what I found, looks like the max recommended is 1.35v for both VCCIO and VCCSA. Would that be fairly easy to run DDR3 under these values or it is a lottery?

The clock does not matter, right? What matters is to set safe values for VCCIO and VCCSA to don't degrade the IMC, right? But would that be doable for most DDR3 memory sticks or not? Would that incur in higher timings, slower memory?

NOTE: sorry, the "quote" button is not working.

 

[13thmonkey]

The clock only matters in that it will more likely to be stable at a given voltage if it is slower. I.e. to get faster you need higher voltages, so if you reduce the voltage you must reduce the clocks, else it'll be unstable.

 

[Contiusa]

Cool, thanks!