Core i9 9000 HEDT series memory rank support?

[Artas1984]

From what i understand all of the Core i9 9000 HEDT series processors for LGA2066 are considered Skylake-X, same as Core i9 7000 HEDT series, meaning they are actually 7-th generation? If that is the case, then these processors only support 16 GB DIMM DDR4 modules in 2Rx8 layout and NOT in 1Rx8 layout? Only the later generation processors support 16 GB DIMM DDR4 modules in 1Rx8 layout? CAN ANYBODY CONFIRM THIS?

I've got a Core i9 9960X and Asrock X299 Taichi motherboard, a combo which simply refuses to work with Mushkin Redline 2X16 GB DDR4 4000 MHz kit (error code 53), despite the fact that motherboard does support RAM up to 4266 MHz. The Mushkin 2X16 GB DIMM DDR4 modules are exactly of 1Rx8 layout, meaning single rank with eight 8-bit chips on one side! Failing with Mushkin, i have replaced the RAM with Kingston HyperX 2X8 GB DIMM DDR4 modules, which are of 1Rx8 as well and they work.

I still need to buy RAM, but if only dual rank 16 GB modules are supported by Core i9 9960X, and not single rank, the selection becomes somewhat limited..

 

[jon_joy_1999]

Your Core i9960x supports up to 128 GB of RAM, depending on the memory type. However your motherboard, specifically the Intel x299 PCH, does not support 1Rx16 memory modules.

Also, an aside note, 16 GB modules aren't identified as *Rx8.

 

[Artas1984]

Your Core i9960x supports up to 128 GB of RAM, depending on the memory type. However your motherboard, specifically the Intel x299 PCH, does not support 1Rx16 memory modules.

Also, an aside note, 16 GB modules aren't identified as *Rx8.

I know that the X299 does not support 1Rx16 modules, i am not even looking at them, but you are wrong: 16 GB modules can be 1Rx8 as well as 2Rx8. Here is an example (download the Kingston PDF spec and you will see what i am talking about):

RAM kit consisting of two 16 GB single rank modules: KINGSTON KF432C16BBK2/32

RAM kit consisting of two 16 GB dual rank modules: KINGSTON KF432C16BB1K2/32

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Anyway the low reply activity dumb-founds me, where the heck are all the old guys? Taking vacation? The question about Skylake-X compatability still persists. And please reply only those who know exactly!

 

[Speedyblupi]

Also, an aside note, 16 GB modules aren't identified as *Rx8.

This isn't true at all.
*Rx8 means the module uses RAM chip with 8-bit wide buses, therefore 8 chips per rank (because each rank is 64 bits wide, and 64/8 = 8). Almost all 16GB DDR4 modules are 1Rx8 or 2Rx8. You can get 1Rx16 (1 row of 4 16-bit chips) and 1Rx4 (1 row of 16 4-bit chips) 16GB DDR4 modules, but they're very rare.

From what i understand all of the Core i9 9000 HEDT series processors for LGA2066 are considered Skylake-X, same as Core i9 7000 HEDT series, meaning they are actually 7-th generation? If that is the case, then these processors only support 16 GB DIMM DDR4 modules in 2Rx8 layout and NOT in 1Rx8 layout? Only the later generation processors support 16 GB DIMM DDR4 modules in 1Rx8 layout? CAN ANYBODY CONFIRM THIS?

I've got a Core i9 9960X and Asrock X299 Taichi motherboard, a combo which simply refuses to work with Mushkin Redline 2X16 GB DDR4 4000 MHz kit (error code 53), despite the fact that motherboard does support RAM up to 4266 MHz.

The ASRock X299 Taichi motherboard's memory QVL includes 16GB 1Rx8 modules, however the fastest 16GB 1Rx8 (single-sided/SS) module on the QVL has a maximum transfer rate of only DDR4-2400. If the JEDEC profile of the Mushkin Redline kit is rated for a higher speed than this, it may not work correctly, and it's very unlikely that you would be able to get it to work at DDR4-4000 even if you manage to get it to boot.

Some other X299 motherboards are validated for higher speeds with 16GB 1Rx8 modules (e.g. the ASUS Prime X299-A is validated for speeds up to DDR4-3200 with SS 16GB modules). A different motherboard might allow the RAM to at least work at JEDEC settings (the default setting should be DDR4-2666, as this is the highest transfer rate that Skylake X CPUs officially support), but would still potentially have problems if you try to enable XMP.

Skylake X processors use a different memory controller to standard Skylake and Kaby Lake desktop processors, so do not have the exact same limitations (Skylake X supports unbuffered ECC memory, and the Skylake X Xeon models also support registered ECC memory, including 1Rx4 and 2Rx4 modules), but can still have problems working with 16GB 1Rx8 RAM modules on some motherboards.

 

[jon_joy_1999]

I'm sorry, I must have misunderstood this page about RAM ranks in my research for this question: https://history-computer.com/ram-rank-vs-channel/
I downloaded the spec sheet for both of the RAM modules you suggested, and they are nearly identical. The only differences between them are, in order, the part number, a reference to the number of components and their size, the XMP profile latencies, the document number, and a graphic showing a representative layout of the memory modules and their chips. I don't see where it identifies 1Rx8 or 2Rx8

 

[Speedyblupi]

I'm sorry, I must have misunderstood this page about RAM ranks in my research for this question: https://history-computer.com/ram-rank-vs-channel/
I downloaded the spec sheet for both of the RAM modules you suggested, and they are nearly identical. The only differences between them are, in order, the part number, a reference to the number of components and their size, the XMP profile latencies, the document number, and a graphic showing a representative layout of the memory modules and their chips. I don't see where it identifies 1Rx8 or 2Rx8

Oh, you didn't misunderstand it.
The article is just wrong.
It says "The amount of memory in gigabytes follows the ‘Rx.’ For example, an 8GB single-rank Ram is written as 1Rx8.". This statement is completely false. "x8" has nothing to do with the capacity of the module or of each rank within it, it's the bus width of the individual RAM chips on the module. 1Rx16 8GB modules (with four x16 chips of 16Gb/16 Gigabit capacity each; 16 Gigabits is equivalent to 2 GigaBytes) exist. You can look up "8GB 1Rx16" on a shopping website like Amazon and find several results. If you look at photographs of these modules (at least ones where the chips aren't covered by a heatsink or sticker, and where an actual photograph of the module is used rather than a generic render of a RAM module), it's possible to see that there are only 4 chips.

An 8GB 1Rx16 RAM module. Source: Kingston, via Amazon.

It's actually kind of amazing how many sources get it wrong. Even Crucial's website claims that "x4 and x8 refer to the number of banks on the memory component or chip.", which isn't true either. x4 and x8 DDR4 chips both have the same number of banks (16, split across 4 bank groups of 4 banks each), while x16 chips have half as many (8, split across 2 bank groups of 4 banks each). For DDR5 the number of banks and bank groups depends on both the bus width of the chip and its capacity (8Gb x4 and x8 DDR5 chips have 8 bank groups of 2 banks each, but 16Gb x4 and x8 DDR5 chips have 8 bank groups of 4 banks each, and 16Gb x16 DDR5 chips have 4 bank groups of 4 banks each).

You can see that x4, x8, and x16 are actually referring to the bus width of the individual chips by comparing the specifications of different modules and chips on manufacturer's websites.

By the way, check those spec sheets again. They include 1Rx8 and 2Rx8, respectively, in the "Description" section.

 

[Artas1984]

I don't see where it identifies 1Rx8 or 2Rx8

I can not believe i have to waste my time and point out the obvious things, which you have missed.

 

[jon_joy_1999]

I can not believe i have to waste my time and point out the obvious things, which you have missed.

Yes, well, you didn't. So thank you for responding.

 

[Speedyblupi]

Yes, well, you didn't. So thank you for responding.

Or you could have just read the spec sheet properly before replying. Ctrl+F isn't difficult to use, and the description is on the first page of the spec sheet and clearly visible. Don't be snarky when you're the one who messed up.

 

[jon_joy_1999]

I was perfectly fine leaving the discussion. Speedy pointed it out, I had nothing more to contribute. Artlas quotes me and comes across like he's insulted he had to do something. Well here we go. Have fun chasing, what appears to me, to be imagined problems. I was perfectly fine leaving my bad enough alone.

 

[Artas1984]

Some update! I have gradually updated my old BIOS (which should not have even supported the 9000 series Skylake-X CPU) to the newest stable 2.50 and now the Asrock X299 Taichi does support Mushkin Redline 2X16 GB DDR4 RAM, but only up to 3200 MHz. Anything above 3200 MHz displays error 53. However there is a new outcome out of this test that the 16 GB 1Rx8 DIMM modules are supported.