highest-capacity RAM sticks available today?

[ixfd64]

I'm just curious - does anyone know what are the highest-capacity RAM sticks that are available today?

I know that 32 GB modules have become more common in the last few months, thanks to recent developments by Samsung. However, I've also seen a couple of websites that claim to sell 64 GB sticks in an "8 x 8 GB" configuration.

Normally, an "X x Y GB" memory kit would mean X modules with Y GB each. However, the price for the 64 GB sticks implies otherwise; a single 8 GB stick costs only a little over $100 these days, and eight of them would be around $1,000, not the $4,000 to $7,000 that the sellers are asking for. Yet I could very little information on them.

So are these "64 GB sticks" merely overpriced sets of 8 GB modules, or do they actually exist? I personally believe that they exist but haven't reached the consumer market yet, hence the lack of information.

[fivemack]

The price of the very largest ram sticks has dropped substantially recently, so it's not unreasonable that someone would have pricing left over from no more than a year ago with those very high prices for sets of 8GB sticks.

http://www.memoryamerica.com/dk81024721066au.html is a set of eight 8GB ECC unbuffered modules for about a thousand dollars.

Crucial do appear to have honestly-32GB and honestly-16GB sticks of registered ECC memory for $2800 and $480 respectively.

If you require non-ECC then 8GB is the biggest available and is $300.

Even looking at TPC reports of configurations of truly enormous servers, I haven't seen anything using 64GB sticks.

[henryzz]

How many of these 32 GB sticks can a system with 8 E7-8870 cpus support? Are we looking at a possible 512GB or 1TB of memory in total(2 or 4 DIMMs each CPU)?

[fivemack]

Each E7-8870 has two 28-bit-wide 6.4Gbit-per-second links to an Intel 7512 Scalable Memory Buffer chip. Each SMB chip provides two DDR3 buses, which can each have two RDIMMs of up to quad-rank each. So:

64GB per bus
128GB per SMB chip
256GB per CPU
2048GB per system

However, IBM also provide machines which have additional RAM-extension technology to allow 128 (rather than 64) slots in an 8-processor system;
http://www.tpc.org/results/FDR/TPCE/...fdr.082611.pdf
page 5 contains all the codes you need to order one with 128 16GB modules from IBM. It will cost $210,049, most of which is for the memory.

Cisco have some buffer chips that make eight DDR3 modules appear to be two DDR3 modules to a DDR3 controller, but I don't think they use them in conjunction with the Westmere processors, and I'm not sure whether they support 16G and 32G DIMMs.

[ldesnogu]

Originally Posted by fivemack

64GB per bus
128GB per SMB chip
256GB per CPU
2048GB per system

Are you sure about that? Intel E7-8870 product page says max memory is 32 GB. Something's odd as indeed the IBM system you link to has 2TB for an 8 CPU system; Fujitsu has a similar machine with 2TB. I guess Intel page is wrong...

[Salam Rocky]

cmon i recently saw in the ram wiki that in the jeopardy 30th anniversary 16TB terabytes ram was used and it even worked

so the greteest ram i 16 TB Tera Bytes rm yipeeee i win it

[TheMawn]

The 16 TB of RAM on Wilson would be on some super computer which is more or less composed of many, MANY smaller computers, each of them with their own more reasonable RAM capacity. Wilson was able to answer questions in a matter of seconds whereas the most capable memory controller on a consumer PC would need hours to sort through all of it, let alone actually process any of it. 16TB of RAM probably in sets of 4 GB across 4000 CPUs.


Regarding the memory prices. More recently, it looks like a 64 GB kit which is indeed 8 x 8 GB costs around $650 though a 2 x 8 GB kit costs around $130. The 64 GB kit looks to cost five times as much as four 16 GB kits. That extra cost is likely to have been bigger in the past.

The reason for this is that the kits are rated for a certain channel configuration. When you use two sticks in a double-channel configuration (for doubled bandwidth) the sticks have to be EXTREMELY alike. The compatibility is very fragile, so you'll often see that if you take one stick from two different kits, they often won't work together because of the tiniest of differences.

The 4 x Y GB kits are usually not intended for something like a Haswell or Piledriver (though they WILL work perfectly) which uses dual channel, but for something like IB-E or SB-E which uses quad channel memory. Now, you need four compatible sticks, not just two. The eight-stick kits are still intended for quad-channel systems (I don't know of a dual-channel system supporting eight sticks), but they are sold together and MUST all be compatible with one another.

The hassle of verifying the compatibility or improving the manufacturing process to ensure the compatibility is the origin of the extra cost of 8-stick kits over 4-stick kits, or to a greater extent, over 2-stick kits.


Regarding 16 GB sticks or larger, they do exist as engineering samples. However, I'm sure they're not as reliable as manufacturers would like for the consumer market. The memory density on the modules will mean larger prices, more heat, lower frequencies and looser timings. If 32 GB isn't enough for you, get an Enthusiast chipset from intel and run 8 sticks. If 64 GB is still not enough, you need special hardware, and you have no right to complain that the masses don't have access to that kind of thing because they frankly don't need it. I have 16 GB right now because of future proofing. I haven't come close to using 8GB in the nine months I've had this computer.

ASUS has tested their Z77 and Z87 boards for 16 GB RAM stick compatibility. It's an unofficial yes, if I remember correctly. The boards still only officially support up to 32 GB.

[kracker]

16 GB sticks (ECC) do exist for servers.

[danaj]

Note that most of this thread is over 2 years old.

Certainly 16GB and 32GB ECC sticks exist now, and 64GB LRDIMMs were announced in early 2012. Crucial recently announced 1.35V 64GB LRDIMMs. "fully support Ivy Bridge-E".

[TheMawn]

Ha oops I didn't notice it was 2011. I thought I saw 2013.

[danaj]

I think TheMawn said most of the relevant info for now.

Most supercomputers are clusters now, so total memory interesting but not directly comparable to a single server. The old NCSA Lincoln cluster I used a few years back had 3TB of CPU and 3TB of GPU memory (192 nodes each with 16GB RAM and 4 Teslas with 4GB each). The biggest issues for our use was the interconnect. I see NCSA's Blue Waters is listed at 1.5 petabytes of memory (25 petabytes of disk, 500 petabytes of tape).

For consumer use, the LGA2011 platform should support 64GB using 8 x 8GB, which is fairly reasonably prices and available these days. Good question as to whether they'd take 16GB DIMMs. I don't see any consumer 16GB modules on newegg, so it certainly isn't mainstream. All the 16GB and 32GB modules I see are registered ECC.

Without going totally crazy, but leaving the consumer side, Supermicro has some sub-$500 dual LGA 2011 motherboards with 24 slots supporting up to 768GB using RDIMMs or 128GB using consumer DIMMs. The Xeon E5-2600 processors plus all that memory will set you back a bit. There are lots of choices for 16-slot dual-2011 motherboards if you only need 512GB max. For single LGA 2011 server motherboards, Asus's sub-$300 Z9PA-U8 model indicates it supports up to 256GB in 8 slots using LRDIMMs, so 32GB LRDIMMs.

Whether these would support the new 64GB LRDIMMs, I'm not sure. You probably want to call before signing the purchase order for a TB.