And does the Intel guy's statement "Look at the voltage needs for DIMMS, the likely cause is it's running at 1.5V and may need 1.6V to run at 1600Mhz" make any sense at all?
Could it in fact be that some need a little more voltage?
Thanks for your valuable input again Scott.....it sure is a complicated situation.
I did phone some local PC suppliers and apparently none of them have had any memory issues with the 3930k in Australia at least....
chances are they never checked the speed of which the ram is running at.
its most likely downclocked.
however I hear what you are saying and understand that you are in a very good position to know what is going on.
Some thoughts in mind are:
- We are on to the 2nd stepping for the 3930k which I think was brought about due to another issue (still 1st stepping for 3820)...do your tests relate to the new stepping for 3930k?
- Could the problem be limited to a small batch of 3930k/3820 and perhaps you have only tested CPUs from that batch?
highly unlikely we go thru at least a dozen 3930k a week, rarely sell the 3820
that and the 3770k are the 2 processors we sell the most of.
this issue happened with engineering samples of the 3930k as well as full release stepping and i am sure the 2nd stepping.
- For the purpose of your pro DAW PCs are you needing to test/burn in the systems using more thorough tests with higher pass requirement than most other situations such as gaming and general business use?
well maybe its because of what we do vs what others do not do.
before windows ever goes on the system we run memtest over night i think 4 full passes and if the system has 64 gig ram that takes like a whole day just for one pass (18-24 hours)
then after windows and tweaks it gets get benchmarked with Sisoft and then burned in again with sisoft (we stress test ram and CPU subsystems) again over night or longer. takes days to leave the build area and get over to QA.
we set everything in the bios manually to run at full tilt. (OCed or not)
thing is we never never OC the ram. it stays @ 1600, nor do we try to lower the CL settings etc so its not like we are trying to push the ram beyonds its Eeprom specs. and we are the ones who specifiy what we want programmed in the Eeprom and trust me its not aggresive we are looking for stability...
- Could at least part of the problem be the type of motherboard used?
nope when a new processor comes out (before market) we try numerous manufacturers and models (gets expensive and most of us are sick of upgrading our systems yeah i know it sounds odd)
then when retail is released we try a few of the favs again as thier bios are more tweaked at that point (sveral revs later). and then when a new revision comes out we may try a few more again..
plus we see this issue on dual Xeon boards (we use 2 different ones for those) and there is far less tweakability on a server board.
look i can go buy some different ram options and get maybe 50% of them to work on X79 particularly the higher speced (1866 and above) and will have to down clock or down volt (NOT upvolt)
or raise the Cl settings etc to higher than recommended..
we even had issues with samsung origial 8gig sticks due to how they were programmed.
what works best is the higher binned ram.
Jedec spec is 1600 yet there is ram for sale that sold as DDR3 2400 actually 2800 now..
to be clear no memory manufacturer actually makes DDR3 2800 what these guys are doing is binning the best ram from the best chips..
this is basically what we buy. the manufacturer we use gets us only tier 1 chips ( its Elpida FYI) and bins them. we pay out the butt for these.
as i had said before we have had to send back whole orders (several hundred peices) even with these guys as they used a different chip or maybe the Eepron was not as it should have been..
then we have a 2-3 day delay in system building which kills us and backs us up ever farther (we are nearly a month before a system ships after order already)
again not saying you cant buy ram that will work. the issue with saying brand x works is all these guys bid on ram and will switch chip brands for $.25
so while x brand worked last week what they are shipipng this week may not..
the other aspect to this is lets say you buy 16 gig ram and later you want to add 16 more. good luck getting the same chips even though the brand name and model # is the same.. mixing chips and Eeproms do not work too well especially on X79.
best advice i can give is to buy over speced ram (1866 and above) and then run it @ 1600 manually setting the timings
yes 1.5v by being over speced its been binned(tested) to be the best.
i asked my head tech and he said looks like Gskill has been doing fairly ok..
(as in standard 1.35v 1600)
as much as i would love to move to cheaper ram i still have the issue of compatibilty later on. i get at least 3 emails a week about upgrading ram on a system from 1-3 yrs ago..
with older system it no biggy from 2-3 yrs from now when they have 2011 platform it will be..
Also if anyone could also please clarify a couple of other points it would be greatly appreciated.....
- I am thinking it would be best to go for the memory with the lowest CL spec.....or is it pointless paying extra for low CL past a certain point?
- I also seem to remember reading in Wikipedia that to use the full memory bandwidth of socket 2011 you need to fill all 4 memory channels is that correct? For instance if only installing 16GB would a 4 x 4GB kit give the full memory bandwidth and a 2 x 8GB kit only half the bandwidth?