I just got 2x 4Gb form OWC to put in my 2010 2.8GHz quad core. I put them in slots 1 and 2. I put two of the stock 1Gb sticks in 3 and 4. Only the 2 4Gb sticks are being seen. I thought two pairs of two would work.
Got a tip for us?
Let us know
Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
not all memory showing
- Thread starter Phillie14586
- Start date
- Sort by reaction score
Though all the sticks you have are Unbuffered ECC (UDIMM), those sold by OWC work with other sticks properly, if at all (includes both the OEM sticks and OWC's other UDIMM's of smaller capacities). 
If you look at OWC's site a little more carefully, this is mentioned.
If you look at OWC's site a little more carefully, this is mentioned.I just got off a chat with OWC and they say they do not know of any memory modules that their memory is not compatible with. They suggested flashing the PRAM and I did but no fix.
I just took out the 2 1Gb modules and reinstalled them and everything is working. My luck with computers is not going well these days but at least I have solved one problem. Now if I could just get my hard drives working.
This issue has existed with the Nehalem based systems from the moment they began selling their 4GB DDR UDIMM's. If you search MR, you will find it mentioned in multiple memory threads for the 2009/10 systems.
Oddly enough, I just took a look at their site again, and that information seems to have been removed (or I'm just blind). Assuming they did remove that information, that would explain why the tech told you what they did.
And you've just proven pulling the smaller UDIMM's actually worked in terms of getting your 4GB UDIMM's to show up properly.