One of the last things I purchased for my VMware lab is the memory for my Supermicro X8SIL-F motherboard. This was mostly due to the fact that they make the memory information regarding the motherboard a bit confusing. At first I thought I would get 1333mhz memory. Then I realized that 1333mhz memory is a pricey premium. It makes much more sense to go with 1066mhz memory. Supermicro has two specific pages that are helpful regarding memory selection for this motherboard. The first is the Tested Memory List which is linked off the motherboards homepage. This allows you to select either 1066mhz or 1333mhz unbuffered or registered memory and select various sizes. More importantly however is the following chart which you can on the motherboard page under the System Memory section:
One of the key takeaways from the above is that you want to populate the memory in pairs to take advantage of interleaved memory. There are two types of memory supported, Unbuffered (UDIMM) and Registered (RDIMM). If you want to get the most amount of memory on the board, us 2Gb x8 DRAM’s. You can check with the manufacturer to see if the memory meets specifications. I personally went with Registered Dual Rank memory. I went with Crucial CT51272BB1067, and got a decent price at Buy.com. You will probably find that a lot of the memory out there is Quad Rank memory. This includes the recommended memory list when you search off Crucial’s website. Take a look at the chart below:
The issue is that if you use 1066mhz RDIMMs and you populate 2 DIMMs per channel (to get a total of 16GB’s), you will dumb down your motherboard to an 800mhz memory bus! This is not obvious and I have seen a lot of people use the 1066mhz Quad Rank memory on this board. This is why I opted for the Dual Rank memory. If single rank memory exists it’s likely expensive as the chips are more costly. Just like with compromising with 1066mhz memory over 1333mhz memory I decided to go for value.
I have not yet received the memory or had time to test, but I will post a follow-up. The only advantage to going with Quad Rank memory is that you could populate the board with 32GB of memory, but at the sacrifice of memory speed. 16GB is plenty, as I plan to run two ESXi hosts.