A Close Look at Intel Optane DC Persistent Memory Modules

By Patrick Kennedy

Intel Optane V DDR4 DIMM Underneath Controller Side
Intel Optane V DDR4 DIMM Underneath Controller Side

In 2019 one of the hottest technologies is going to be Intel Optane DC Persistent Memory. This is the long-awaited marriage of 3D XPoint memory and the DDR4 memory bus. Today we have something of a sneak peek. We are going to take a 128GB Intel Optane Persistent Memory DDR4 module, and open it up. Until now, Intel Optane DC Persistent Memory has mostly been photographed with its big black heat spreader. We ended up with a handful of modules not from Intel, nor a system provider, but a handful to use. Intel announced at its Data-Centric Innovation Summit that it started shipping modules for revenue. If you are a hyper-scaler you probably already have Optane. If you are a normal enterprise, Intel does not want you to have Optane just yet. However, here we are with live modules and it is time to open them up.

Peeling Back the Intel Optane DC Persistent Memory Modules

First off, we had not seen the modules side-by-side with DDR4 memory. So we grabbed two modules from the photography studio. You may have seen these modules in several STH reviews, the Micron/ Crucial DDR4 modules lasted about 6 months before they failed in different systems only three weeks apart. They were not the perfect comparison, but you can see the Intel Optane DC Persistent Memory module in the middle. All of the PCB dimensions line up with the bottom “label” side of the DDR4 sticks below:

Intel Optane V DDR4 DIMM Front And Back 2
Intel Optane V DDR4 DIMM Front And Back 2

Here is the module flipped over. You can see the notches now align with the back of a normal DIMM. Other features to note are the large black heat spreader and metal clips. The STH blue electrical tape is being used to cover up the Optane DIMM markings.

Intel Optane V DDR4 DIMM Front And Back
Intel Optane V DDR4 DIMM Front And Back

Pulling off the cover was a fairly easy affair. Simply remove the clips, then the heat spreader can be gently pried loose. We are not going to suggest you do this as the module depicted in these photos has not been confirmed to work again. You will notice a thick thermal paste. The thermal solution is far from some of the decorative solutions we have seen on some consumer parts. Intel is using some thick paste which is fairly hard. That makes sense since Intel would not want thermal paste leaking into the DDR4 socket.

Intel Optane V DDR4 DIMM Underneath Controller Side
Intel Optane V DDR4 DIMM Underneath Controller Side

One can see a total of six Optane or 3D XPoint packages flanking the Intel Optane controller on this side which would be the label side of a standard DDR4 DIMM. In the top corner, we have a Winbond IC.

On the flip side, there are five more Optane packages giving this 128GB module a total of 11 packages. This is fascinating on a number of levels. Not the least of which is that the 380GB Intel Optane M.2 NVMe SSD had only 7 packages. Intel is using 57% more Optane packages for about 34% of the capacity. Although we are not showing the package markings here, it seems like Intel may have some over-provisioning going on. It may also need more packages just to fill the memory channels. In a non-ECC DDR4 DRAM module you would expect to see 8 or 16 DRAM packages. In ECC memory you would expect to see multiples of 9 (8 data plus 1 parity.) Eleven packages is, different.

Intel Optane V DDR4 DIMM Underneath Controller Side 2
Intel Optane V DDR4 DIMM Underneath Controller Side 2

The other side also shows perhaps the most astonishing feature. On the other side of the module from the Optane controller is a DDR4 DRAM module, this one from SK.Hynix. Model number H5AN4G8NAFR-TFC. We are not sure why Intel would not use a Micron module here since Micron has been the manufacturing partner for 3D XPoint thus far.

One other feature our readers may have noticed are small rectangular chips near the DIMMs pins. We had an inclination of what these were, and double checked the markings that were bordering on microfiche size print. They are indeed Micron LRDIMM buffer chips as we can see DDR4DB02 marked on the nine chips.

Here is the video of de-lidding the DIMMs:

Final Words

It did not work on current Intel Xeon Scalable Skylake-SP parts and BIOS, nor did it work with AMD EPYC or Marvell ThunderX2 out of the box. We know Intel has the Optane Persistent Memory DIMMs working with Skylake-SP, but it looks like we are going to see this alongside Intel Xeon Cascade Lake SKUs. We expect that unless Intel feels extreme competitive pressure, it is going to reserve Optane Persistent Memory support for higher-end SKUs like Intel Xeon Platinum like it was planning to do when Intel OPM was set to launch alongside Skylake-SP.