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How many GB memory does Ryzen 1800X Maximum support?

Edgar R. Zakarian
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Go to solution Solved by mariushm,

It supports up to 4 memory sticks , and the biggest memory sticks you can buy these days are 16 GB, so that means you can use 4 x 16 = 64 GB of memory.

 

The processors support ECC memory (unbuffered, unregistered), AMD doesn't actively disable it, they just don't validate particular memory sticks as they would validate on server platforms.

So if you put ECC memory sticks the processor will use the ECC functionality. (provided the motherboard BIOS doesn't set the ECC to disabled by default and hide the BIOS option)

 

 

// In theory, 64bit processors can access up to 2 ^ 64 bits of memory, but to make processors simpler and faster (less transistors), the current processors use only 48 bits (the first 64bit processors were limited to 40bit).

So basically pretty much all 64 bit processors these days have a virtual address space of 2^48 = 281,474,976,710,656 bytes of memory, which is equal to 256 TB of memory. There just aren't motherboards with enough memory slots and memory sticks with big enough memory chips to reach that size.

 

As far as I'm aware, the biggest size memory chips available in volume are 8 Gbit (1 GB), so ram manufacturers use 8 or 16 such chips to make 8 GB or 16 GB memory sticks.

 

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Some sources say it supports ECC memory, does it?

 

How many GB of memory does it support at max?

 

I know some I7 intel cpu's support up to 128 GB or more.

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It does support ECC memory, but not validated. 

How much memory it supports, depends on the board you're choosing.

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9 minutes ago, yathis said:

What does the specifications list?

AMD's website said nothing about capacity. which is why I was asking here.

AMD Ryzen R9 5900X  | Arctic Liquid Freezer II 360  |  GIGABYTE X570S AERO G  |  2x32GB G'skill TridentZ 4000MHz  | MSI RX 6900 XT Gaming Z Trio 16GB |  Dark Base Pro 900 (Orange)  | TOSHIBA 4TB 3.5" Drive - Game Drive | Crucial MX200 250GB 2.5" SSD - Boot Drive | Cooler Master V750 PSU |

 

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15 minutes ago, nerdslayer1 said:

there is a thing called google that told me 64gb, 

Mind posting the source?

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1 minute ago, Edgar R. Zakarian said:

AMD's website said nothing about capacity. which is why I was asking here.

Motherboards dont list the amount of ram that can be installed. I find that strange!

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6 minutes ago, Edgar R. Zakarian said:

Mind posting the source?

reviews, publications, amd events, interviews. 

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It supports up to 4 memory sticks , and the biggest memory sticks you can buy these days are 16 GB, so that means you can use 4 x 16 = 64 GB of memory.

 

The processors support ECC memory (unbuffered, unregistered), AMD doesn't actively disable it, they just don't validate particular memory sticks as they would validate on server platforms.

So if you put ECC memory sticks the processor will use the ECC functionality. (provided the motherboard BIOS doesn't set the ECC to disabled by default and hide the BIOS option)

 

 

// In theory, 64bit processors can access up to 2 ^ 64 bits of memory, but to make processors simpler and faster (less transistors), the current processors use only 48 bits (the first 64bit processors were limited to 40bit).

So basically pretty much all 64 bit processors these days have a virtual address space of 2^48 = 281,474,976,710,656 bytes of memory, which is equal to 256 TB of memory. There just aren't motherboards with enough memory slots and memory sticks with big enough memory chips to reach that size.

 

As far as I'm aware, the biggest size memory chips available in volume are 8 Gbit (1 GB), so ram manufacturers use 8 or 16 such chips to make 8 GB or 16 GB memory sticks.

 

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2 hours ago, mariushm said:

So basically pretty much all 64 bit processors these days have a virtual address space of 2^48 = 281,474,976,710,656 bytes of memory, which is equal to 256 TB of memory.

Even though 64-bit CPUs have a theoretical address space this high, pretty much every CPU in production cannot address this much in reality. Intel ARK specifies actual addressable ranges. The AMD spec page does not specify max addressable range.... how odd.

Here is an intel ARK page for example... look at "Max memory size" https://ark.intel.com/products/94189/Intel-Core-i7-6800K-Processor-15M-Cache-up-to-3_60-GHz

Quote

and the biggest memory sticks you can buy these days are 16 GB, so that means you can use 4 x 16 = 64 GB of memory.

This isn't true for ECC DIMMs, which Ryzen supports. I have some 32GB ECC DDR4 DIMMs at home that I'll try to test out tonight on my Ryzen box.... These DIMMs are Registered ECC though and I believe Ryzen only support Unbuffered memory.

 

I'll test it and let y'all know.

 

Remember also that Ryzen memory support is slower with all four slots populated. Ram speeds remain full when only 1 DIMM per channel is populated.

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23 minutes ago, AlexCo said:

Even though 64-bit CPUs have a theoretical address space this high, pretty much every CPU in production cannot address this much in reality. Intel ARK specifies actual addressable ranges. The AMD spec page does not specify max addressable range.... how odd.

Here is an intel ARK page for example... look at "Max memory size" https://ark.intel.com/products/94189/Intel-Core-i7-6800K-Processor-15M-Cache-up-to-3_60-GHz

 

Yes, like I said, even though the architecture allows up to 64 bit , all processor manufacturers simplify their processors' design to use less bits so the actual total memory that processors can play with. The most common values are 40 bit (1TB) and 48 bit (256 TB)  but there were some processors with as little as 36 bits (some Intel cpus).

 

For that particular Intel processor, the maximum physical memory is 128 GB because the CPU has a memory controller with 4 channels, which allows for 4 x 2 x 16 GB = 128 GB of memory. The actual memory the processor can play with (includes page file and other things) is much larger than that.

With Ryzen, AMD simply decided to go in the middle with just 2 channels, each with 2 slots, so you have a maximum of 64 GB.

 

23 minutes ago, AlexCo said:

This isn't true for ECC DIMMs, which Ryzen supports. I have some 32GB ECC DDR4 DIMMs at home that I'll try to test out tonight on my Ryzen box.... These DIMMs are Registered ECC though and I believe Ryzen only support Unbuffered memory.

I'll test it and let y'all know.

 

Remember also that Ryzen memory support is slower with all four slots populated. Ram speeds remain full when only 1 DIMM per channel is populated.

Registered or Buffered memory sticks aren't supported.

 

Yeah, Ryzen supports officially 2667 Mhz for single rank , 1 memory per channel (2 sticks in total) .. 2400 Mhz for dual rank, 1 memory per channel , and then we have 2133 Mhz for single rank/ 4 memory sticks and 1866 Mhz for dual rank/4 memory sticks.

This doesn't mean higher frequency memory sticks aren't supported through. It will just take a couple of weeks for BIOSes to bring better memory compatibility

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3 minutes ago, mariushm said:

The most common values are 40 bit (1TB) and 48 bit (256 TB)  but there were some processors with as little as 36 bits (some Intel cpus).

Missed the line where you wrote that in your previous post. Good info, thanks for the write-up!

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