RDIMM on X99 mainboards with i7

Hey folks,

I'm planning on building a X99-System I had a dual cpu Westmere-EP and an Ivy-Bridge-EP workstation, both with registered DDR3 modules because they were very cheap in used condition.

Prices on DDR4-modules are high yet but when the first servers are upgraded prices for the used 4GB or 8GB registered modules will be low *hopefully*.

Since I can't decide whether to use a i7-5xxx cpu or Xeon E5 v3 in the long run (and maybe have to test other CPUs) here my Question:

Can I run registered modules with e.g. a i7-5820k? In most cases registered modules come with ECC and i know that ECC isn't supported by the i7 and hence won't be used. But what about the registered thingy with i7? It's pretty unclear to me...

The mainboard for my build will probably be the GA-X99-UD4. In revision 1.1 there's support for RDIMM 1Rx8/2Rx8/1Rx4/2Rx4 configuration, in 1.0 only RDIMM 1Rx8. Has there been any change in the X99 chipset?

A big thanks in advance for your help on clarification
outlawx

You won't be able to use ECC or Registered memory with an i7, it has to be a Xeon.
Even then, only certain motherboards support ECC or Registered memory.

Thank you for your quick reply

I know that the ECC feature is disabled with non Xeon but normal UDIMMs with ECC will nearly always work on normal mainboards.

The question is will the mainboard recognise registered modules without xeon?

The specs for the Gigabyte board http://www.gigabyte.com/products/product-page.aspx?pid=5284#sp

You need Xeon.

On most X99 boards unbuffered ECC will work even though they're not on the compatibility list. Some manufacturers have them, some not. Registered modules never work on desktop boards and I don't think you make them work on X99 boards.

Woomack said:

On most X99 boards unbuffered ECC will work even though they're not on the compatibility list. Some manufacturers have them, some not. Registered modules never work on desktop boards and I don't think you make them work on X99 boards.

Click to expand...

Should clarify that ECC will only work with Xeon, not with i7.

That's the theory. I'm not sure how it looks in real as on every other desktop chipset non-registered ECC works with regular CPUs. However X99 motherboard manufacturers say they tested it with Xeons only so I'm not sure if it's because they didn't make full tests with i7 or it's simply not working.
ASUS says ECC isn't working at all but still supports Xeons. ASRock says non-registered ECC works on their boards and now I even see that registered should work but with Xeons:
"Supports DDR4 UDIMM ECC*, RDIMM Memory (*ECC is supported with Intel® Xeon® processors.) "
http://asrock.com/mb/Intel/X99 Extreme11/index.us.asp

Digging some more, MSI supports ECC and even registered but " Supports RDIMM 1Rx8 memory module(Operates in non-ECC mode)"
http://www.msi.com/product/mb/X99S-XPOWER-AC.html#hero-specification ( detailed specs tab ).
I guess they missed something in description as there is no word about unbuffered ECC. When I got MSI X99S Sli Plus then specification was saying it doesn't support any ECC memory.

Gigabyte X99 SOC has exactly the same description as MSI:
"Support for RDIMM 1Rx8 memory modules (operates in non-ECC mode)"
http://www.gigabyte.com/products/product-page.aspx?pid=5129#sp

Simply ECC is not officially supported on these chipsets and looks like every manufacturer is adding slightly different compatibility ( through BIOS etc ).
When we add all info from manufacturers sites then it looks like:
ECC unbuffered = works on every board with any CPU but needs Xeon to enable ECC mode
ECC registered = works on some boards and depends from manufacturer may require single rank modules ( read 4GB looking at current availability of DDR4 ).

Hello Woomack,

thank you very much for your comment

Woomack said:

ECC registered = works on some boards and depends from manufacturer may require single rank modules ( read 4GB looking at current availability of DDR4 ).

Click to expand...

Gigabyte even announced new revisions of some boards which improves RDIMM-handling, look at
http://www.gigabyte.com/products/product-page.aspx?pid=5123#sp versus http://www.gigabyte.com/products/product-page.aspx?pid=5284#sp
Maybe there have been any changes to the X99-chipset?

And the question still stands: Will RDIMM be running with i7?

best wishes

I would ask manufacturer as it's not clear looking at specification and I have no ECC DDR4 around to test it. Main problem here is that all manufacturers are saying that Xeon is required to run ECC mode but none of them said if you need Xeon or i7 to run registered modules.

ECC and non-ECC modules cost about the same if you check brands like Crucial. Used will be in similar prices at least for some time. Prices will be only lower on single modules which someone got with server. If it won't be some mass sale from couple of the same servers then I don't think you will easily find the same modules in the same ranks based on the same IC.
I see that many X99 owners got cheaper DDR4 kits and wait for something "better". Many got cheapest Crucials and now try to sell them to get something from higher series so I think you will have similar chance to get desktop and server memory in similar price. Hard to say exactly how much desperated people can you find on auctions.

Hi Woomack,

thank you for your answer. Already sent an e-mail to Gigabyte (no answer so far).

Actually you totally get my problem on memory prices Some used server modules are very cheap to come by in the near future whereby demand on UDIMMs will be high with the release of the next DDR4 platforms like Skylake...

So maybe I'll only get a 4core Xeon for the initial setup...and look out for a used >=6core Xeon E5

I'll keep you updated

sunny greetings
outlawx

Sandy Bridge E3/E5/E7s are coming down on Ebay, I've been noticing, as I have this weird fascination with server parts.

Yeah, for C60x/X79 there's tons of stuff out there. The Thinkstation D30 will get a 2nd 6core E5 v2 in the near future...and memory upgrades to 2x 64GiB

I think that better is to look for Ivy Bridge-E based Xeons as you can find something 8-12 core in not so high price. I mean they're about 10-15% faster core to core than SB based Xeons and usually have larger cache so will last for longer.
I was looking for 8-12c IB Xeon for my X79 board but all I could find were ES chips and buying them is like stealing, not to mention that some early ES batches had problems with stability.

Skylake is probably delayed till Sept 2015 and next update for 2011-3 socket will be at the beginning of 2016 ( if there won't be any delay ). I bet there will be motherboard refresh before premiere so buying mobo +low Xeon right now is not best idea.

So far I see that SB/IB based Xeons are working with higher bclk but Haswells-E are not. I haven't seen anyone running Xeon v3 @125 or 167 bclk straps and this is main reason why I'm not looking for one of these Xeons even though 8 core costs not much more than 5930K.

Hi Woomack,

for the Thinkstation D30 i'll just get a second E5-2630 v2 to keep it symetric - and it's already Ivy Bridge. With these workstations there ain't anything to overclock, also they are in production use

For the upcoming X99 build it's also about stability, no need for overclocking. I just want the possibility for >=6core and I will need huge amounts of cheap RAM.
The perfect solution would be the next gen workstations like Thinkstation P500 or HP Z440 but way to pricey for the moment - and traditionally they won't work with the next CPU refresh (like SB/IB on X79 vs. 2 HW revs on D30 and Nehalem/Westmere on X58 vs. 2 HW revs. on Z400/Z600/Z800 and so on...)

So my plan is to get a Gigabyte X99 rev 1.1 mainboard, have a decision between i7 and Xeon, small kit of UDIMMs and a (some) stick(s) of RDIMM to test with i7

btw: I don't know if it is allowed to say in these forums but all the boxes have to run with OSX (for a particular piece of software), so a mainboard switch to a different model is a no go, an upgrade/switch on cpus, ram etc. no problem at all. The Arch Linux is for debugging purposes...

Keep you posted...

greetings from Szczecin

Cheapest 4GB ECC Reg I found

http://eu.crucial.com/eur/en/memory/ct4g4rfs8213

http://www.ceneo.pl/32181423#mh=y6v...93iBV1_yCOaIu9igYSNV3OBnaduB4GzRKj33z8us96dg2

I would get 5820K + standard RAM and work on this for next year+ till prices drop. i7 has higher clock than Xeons and I doubt you will find anything in similar performance and price. In a year+ you can start to look after 8-10 core Xeon but I doubt that price will be low enough.

I'm selling now 32GB Crucial 2133 for 1200zł. If you are interested then send me pm and I will send you allegro link.

ATMINSIDE said:

Should clarify that ECC will only work with Xeon, not with i7.

Click to expand...

Why are you talking about the thing you don't know with such confidence? ECC UDIMM will surely work with any desktop motherboard and desktop processor. The processor will simply ignore pins for the parity memory chip. Check out the schematic of any UDIMM module https://www.micron.com/~/media/docu...odules/unbuffered_dimm/ddr4/asf9c512x72az.pdf
UDIMM is a shortening for unregistered memory. The other term is used for buffer is register. So UDIMM has no buffer for a command, RDIMM has one. Chips on a memory module are connected to command pins in parallel and in UDIMM chips are directly connected to processor that makes it virtually identical to any other nonECC module if processor do not know about the parity chip it will simply ignore its data pins. Its not ECC who render memory module incompatible, its buffer or register. There are ECC memory modules that do not have a buffer. Also they are as fast as any other memory module because there is no delay in operation. Register is useful when you have 16+ modules in a system and processor can't pump the memory bus fast enough in one clock tick.
Also X99 chipset is compatible even with registered memory. Almost all X99 motherboards do support RDIMM as well. RDIMM modules are on the QVL list of ASUS X99-A/PRO/DELUXE. But in this case you wouldn't be so sure... its up to marketing planning to artificially disable the needed functionality. But unregistered memory will work anyway.

unclocker said:

Why are you talking about the thing you don't know with such confidence? ECC UDIMM will surely work with any desktop motherboard and desktop processor. The processor will simply ignore pins for the parity memory chip. Check out the schematic of any UDIMM module https://www.micron.com/~/media/docu...odules/unbuffered_dimm/ddr4/asf9c512x72az.pdf
UDIMM is a shortening for unregistered memory. The other term is used for buffer is register. So UDIMM has no buffer for a command, RDIMM has one. Chips on a memory module are connected to command pins in parallel and in UDIMM chips are directly connected to processor that makes it virtually identical to any other nonECC module if processor do not know about the parity chip it will simply ignore its data pins. Its not ECC who render memory module incompatible, its buffer or register. There are ECC memory modules that do not have a buffer. Also they are as fast as any other memory module because there is no delay in operation. Register is useful when you have 16+ modules in a system and processor can't pump the memory bus fast enough in one clock tick.
Also X99 chipset is compatible even with registered memory. Almost all X99 motherboards do support RDIMM as well. RDIMM modules are on the QVL list of ASUS X99-A/PRO/DELUXE. But in this case you wouldn't be so sure... its up to marketing planning to artificially disable the needed functionality. But unregistered memory will work anyway.

Click to expand...

Intel has ECC listed on their processor pages. It isn't compatible with the i7 chips.

http://ark.intel.com/products/82932...-Cache-up-to-3_60-GHz#@product/specifications

ATMINSIDE said:

Intel has ECC listed on their processor pages. It isn't compatible with the i7 chips.

http://ark.intel.com/products/82932...-Cache-up-to-3_60-GHz#@product/specifications

Click to expand...

Some processors do support ECC. That means they can benefit from DIMM modules with parity chip. The processor that has no idea about ECC will work smoothly with ECC UDIMM. There is no separate standard on ECC memory. Codes are corrected in memory controller in CPU. ECC module only has additional ninth parity chip for every eight of them on both sides/ranks. NonECC processor has this additional pins unconnected and will work with ECC UDIMM. There are standards for UDIMM http://www.jedec.org/sites/default/files/docs/4_20_26R24.pdf and RDIMM http://www.jedec.org/sites/default/files/docs/4_20_28R24.pdf only. RDIMM require additional support from memory controller not ECC.

unclocker said:

Some processors do support ECC. That means they can benefit from DIMM modules with parity chip. The processor that has no idea about ECC will work smoothly with ECC UDIMM. There is no separate standard on ECC memory. Codes are corrected in memory controller in CPU. ECC module only has additional ninth parity chip for every eight of them on both sides/ranks. NonECC processor has this additional pins unconnected and will work with ECC UDIMM. There are standards for UDIMM http://www.jedec.org/sites/default/files/docs/4_20_26R24.pdf and RDIMM http://www.jedec.org/sites/default/files/docs/4_20_28R24.pdf only. RDIMM require additional support from memory controller not ECC.

Click to expand...

I'm well aware that some processors support ECC. The Xeon lineup does.
Intel lists compatibility on their site per CPU for a reason.

ATMINSIDE said:

Intel lists compatibility on their site per CPU for a reason.

Click to expand...

The reason is to let costumer know that the CPU can benefit from ECC or support RDIMM. Why did you conclude that i7 that do not list ECC as a feature will not work with ECC UDIMM? If they don't list PCIe3 support on a particular processor it wouldn't mean that the PCIe3 card do not work with this CPU on PCIe2 speed. In other words ECC UDIMM is backward compatible with non ECC UDIMM motherboard and CPU.