Does i7 5960X support 128 gb of ram?

[BTeam]

Does i7 5960X support 128 gb of ram? , there are x99 mobos that support 128gb ram , but it says i7 5960x i7 5820k and i7 5930k only supports 64

[JBour6]

46 bits can address a total of 2^46 locations. If those addressable location is one byte(i.e 8 bits is current standard) then 46 bits translate to 2^46 bytes. 1GB(giga byte) is 2^30. So

46 bits physical address translate to 2^46/2^30 = 65536 GB. You said 70,368 GB. Please clarify.Also you said limitation of CPU specs for this CPU is 64GB due to DIMM type,size,load. Does this mean "Limitation of CPU specs for this CPU is 64GB due to DIMM type,size,load made by CPU manufacturers or due to DIMM type,size,load of RAM memory of the current industry"?

[KTran10]

Since your CPU support UDIMM which might be difficult to find 16GB UDIMM stick, during CPU validation they test with 8GB UDIMM. That is guarantee word, to refuse to support you when you tries to get it up to 128GB. It has nothing to do with physical address.For example they sell you CPU to run 3.5GHz, which mean CPU need to run at 3.5GHz. But CPU can have some margin head room to over clock CPU to 4.0GHz, will you request Intel support to run at 4.0GHz.

[KTran10]

2^46= 70,368,744,177,664B

[EstebanA_C_Intel]

Hello, All:

I would like to investigate a little more on this.

I will be providing you with my outcome as soon as available.

Regards,

Esteban C

[JBour6]

@langtu

It has 46 bit address bus which implies 46 line of micro wires that is connected from CPU to outside-of CPU.

CPU gets the address of location from where to fetch data into its register(mostly Program Counter). Remember this is address not the actual data.If one line micro wire or one bit can have two states then 46 lines of micro wires or bit can have 2^46 states when take together.This implies that theoretically there are 2^46 number of unique locations that can be recognized. CPU has to know location of RAM(or main memory), peripherals, I/O. All these can be given some locations whose total would be 2^46.As I said most main memory are made up of byte sized addresses. If we ignore peripherals and I/O, 2^46 unique addresses can be give to 2^46 1 byte locations. Its not 70,368,744,177,664B = 70,368GB

2^30 B = 1GB

70368744177664 B = 70368744177664 GB/ 2^30 '' = 65536 GB

But due to as you said type of RAM available today or the address bus might be locked down by Memory Controller to operate for lesser number of bits(micro wires) Intel specify that it can support or address 64 GB of main memory. Yes, IO,peripherals and other signalling are not considered in 64 GB. This means 36 bits out of 46 bits is used for main memory. Rest 28 bits are unused or used in some special case to address other location. Also note that some bits may carry signals like whether to read or write into memory and many different purpose.

So I guess unless and until rest 28 bits are not used or some of 28 bits are not used, It can support 128 GB RAM. Notice here that I said 36 bits out of 46 bits implies 64 GB. Inclusion of just one bit i.e 37 can give CPU the power to support 128GB. It wouldn't be much of a surprise that out of 28 bits one bit is not used.

Also it all depends on how the CPU manufacturer or designer restricted the bits utilization.

Need some senior person to comment and close this thread. I tried my best to understand these concepts from scratch.

[KTran10]

If you looked at previous message, I get the system boot up with 128GB. Because the motherboard support Xeon1600 and i7 with RDIMM and LRDIMM. I use i7 with RDIMM and 16GB DIMM module to have 128GB. 46 bits address is a physical wires to map physical memory to 65536 GB. There is no lock down on the bit.

[JBour6]

Yes I saw that. If there is no lock down then it can support 65536 GB of RAM given that motherboard and RAM modules support that too. Then it is all clear. OP should comment about how this thread served him.

Thanks langtu

[Ronny_G_Intel · Accepted solution]

Hello All,

The official answer to this question is 64GB as documented on ARK: http://ark.intel.com/products/82930/Intel-Core-i7-5960X-Processor-Extreme-Edition-20M-Cache-up-to-3_50-GHz Intel® Core™ i7-5960X Processor Extreme Edition (20M Cache, up to 3.50 GHz) Specifications but as the community has posted earlier, there are other possible scenarios. I would encourage the community to share any other findings.

Regards,

Ronny G