Why is GPU-Z showing graphics memory bus width as 64bit instead of 128bit?

[Starjack34]

Hi, i'm new to the forum so excuse me if i do or say anything wrong. I have a almost 10 month old Lenovo laptop with a Core i3-1215U 6-core processor in it . I've been noticing for the past months that GPU-Z keeps showing the bus width for the graphics memory for the integrated UHD Graphics Xe 64EUs GPU as 64bit instead of 128bit, when my laptop has 12GB of RAM that is in dual-channel mode. I posted a screenshots below to prove my point. Will this be addressed soon in a next update? Thanks.

 

[:D:D]

Hi @Starjack34 and welcome.

Unless things have changed then 12GB of RAM means likely running in flex mode. Half of the 8GB module would be combined with the 4GB module to give 8GB of dual channel and the remaining 4GB would run in single channel. Is it guaranteed the shared memory for igpu would only be in dual channel, maybe that's why it's showing 64bit? FWIW my laptop igpu which is 10 years old now shows 128bit on GPU-z 2.54.0 and earlier.

 

[Starjack34]

Well the 8GB is actually one module, soldered on the laptop itself. 4GB is the slotted memory. My system did come with 8GB RAM alone before upgrading with the 4GB RAM stick. I would only wondered if this affect those whose laptop come with soldered memory because some software might have problem reading onboard memory vs slotted memory. Your laptop for instance only has slotted memory (RAM sticks in slots) because obivously you're using an old laptop. That's why GPU-Z is showing yours as 128-bit. I purchase mines last year and is much slimmer, that it doesn't include a cd/dvd drive and it uses a SSD. I don't know what it is really but it doesn't seem to affect my system's iGPU's gaming performance anyway as games were playing at their best. Even if it is i'm running these games with just 64-bit bus width, then i must have a really strong iGPU.

 

[Assimilator]

As @:D:D mentions, your system is running in so-called asymmetric dual-channel mode. In other words, the first 4GB of the 8GB module + the entirety of the 4GB module are being accessed in dual-channel mode i.e. 2x 64-bit, but the remaining 4GB of the 8GB module has nothing to match with and hence runs in single-channel mode i.e. 64-bit. So technically all of these apps are both correct and incorrect.

The only variable here, then, is whether the Intel IGP accesses memory of the first 4GB or the last 4GB of memory i.e. whether it's running in 128-bit mode or 64-bit mode. I don't know if it's possible to determine, but I will defer to @W1zzard in this regard.

 

[Devon68]

What??? Are you comparing the system's memory with the igpu's? The igpu will always be 64 bit, it has nothing to do with the systems ram. Dont think it will go to 128 bit even if it uses system ram.
EDIT: Something I found online
Question "Hi, why is the video core memory width bus equal to 64 bits when I have two sticks of RAM and it should be 128? how can i fix it?"
Answer "
In reference to your question, the reason is, as you can confirm in the link below, that the maximum graphics memory on Windows* 10 and Windows* 11 when using Intel® UHD Graphics is limited by the Operating System to one-half of the system memory. So, if you have 128 bits of memory RAM, that means you will have 64 bits of graphics memory.

 

[:D:D]

Windows* 10 and Windows* 11 when using Intel® UHD Graphics is limited by the Operating System to one-half of the system memory. So, if you have 128 bits of memory RAM, that means you will have 64 bits of graphics memory.

Half the system memory as in if there is 10GB of system memory then up to 5GB can be used for graphics.

Found a video of 2x8GB dual channel and i3-1215U with GPU-Z showing 64-bit while GPU tab of CPU-Z shows 128-bit so it's not because of flex mode as I thought earlier.

Hopefully one of the Dev's will explain.

 

[Starjack34]

"

What??? Are you comparing the system's memory with the igpu's? The igpu will always be 64 bit, it has nothing to do with the systems ram. Dont think it will go to 128 bit even if it uses system ram.
EDIT: Something I found online
Question "Hi, why is the video core memory width bus equal to 64 bits when I have two sticks of RAM and it should be 128? how can i fix it?"
Answer "
In reference to your question, the reason is, as you can confirm in the link below, that the maximum graphics memory on Windows* 10 and Windows* 11 when using Intel® UHD Graphics is limited by the Operating System to one-half of the system memory. So, if you have 128 bits of memory RAM, that means you will have 64 bits of graphics memory."



No i'm not comparing the system's memory with the iGPU's. I'm talking about the bus width reading on GPU-Z as to why it reads 64-bit instead of 128 bit when my system has memory (RAM) that is in dual channel mode. When your system has only one memory slot occupied (now i'm talking about the RAM), the bus width would remain at 64 bit. If it has two memory slots are occupied, them the bus width with go to 128 bit. That is not what I'm experiencing with my system as seen on the GPU-Z of my system's iGPU. Although Assimilator did tell me that my system's memory is running in asymmetric dual-channel mode which i feel is true. Asymmetric means that is not identical or not equivalent. So the 4GB, out of the 12GB RAM, runs on top and is single channeled. Maybe that's why the bus width shows 64 bit, well for the iGPU's interface.

Half the system memory as in if there is 10GB of system memory then up to 5GB can be used for graphics.

Found a video of 2x8GB dual channel and i3-1215U with GPU-Z showing 64-bit while GPU tab of CPU-Z shows 128-bit so it's not because of flex mode as I thought earlier.

Hopefully one of the Dev's will explain.

No, you might be right. If my system's memory is running in asymmetric dual channel mode as Assimilator said, then it's in flex mode. At least according to this guy on reddit:

https://www.reddit.com/r/XMG_gg/comments/iv8b7q

 

[W1zzard]

This looks like a detection bug in GPU-Z, let me look into it

 

[:D:D]

@Starjack34 In your screenshot CPU-Z shows a DRAM clock of 1596MHz, HWinfo 1330MHz and GPU-Z 2660MHz, weird.

If we take HWinfo clock of 1330MHz that gives a DDR speed of 2660MT/s and with dual channel 128bits (which is 16 Bytes) gives 16 x 2660 = 42,560MB/s or 42.56GB/s maximum theoretical bandwidth. Usually I see about 80% or so of that in real life in optimized benches.

DRAM bandwidth can be checked with Intel mlc

Intel® Memory Latency Checker v3.11

Intel® Memory Latency Checker (Intel® MLC) is a tool used to measure memory latencies and b/w, and how they change with increasing load on the system.

www.intel.com

Or if you prefer to target igpu then poclmembench uses openCL

GitHub - kruzer/poclmembench: calculates your gpu memory speed

calculates your gpu memory speed. Contribute to kruzer/poclmembench development by creating an account on GitHub.

github.com

Example of my dual channel DDR3 @800MHz DRAM clock (1600MT/s)

allocated 1476395008 bytes 1.38 GB
Running Bench test on:Intel(R) HD Graphics 4600
Chunk:   0 (   0- 128)MB Speed: 21.15 GByte/s OK
Chunk:   1 ( 128- 256)MB Speed: 21.28 GByte/s OK
Chunk:   2 ( 256- 384)MB Speed: 21.37 GByte/s OK
Chunk:   3 ( 384- 512)MB Speed: 21.35 GByte/s OK
Chunk:   4 ( 512- 640)MB Speed: 21.31 GByte/s OK
Chunk:   5 ( 640- 768)MB Speed: 21.32 GByte/s OK
Chunk:   6 ( 768- 896)MB Speed: 21.25 GByte/s OK
Chunk:   7 ( 896-1024)MB Speed: 21.31 GByte/s OK
Chunk:   8 (1024-1152)MB Speed: 21.36 GByte/s OK
Chunk:   9 (1152-1280)MB Speed: 21.30 GByte/s OK
Chunk:  10 (1280-1408)MB Speed: 21.31 GByte/s OK

Max theoretical bandwidth would be 25.6GB/s

 

[ir_cow]

CPU only has 2 channels. Can't run in single and dual at the same time. Either it's dual channel or single channel, not both.

As for GPUs... Idk.

 

[:D:D]

Dual-Channel Mode – Intel® Flex Memory Technology Mode

The IMC supports Intel Flex Memory Technology Mode. Memory is divided into a symmetric and asymmetric zone. The symmetric zone starts at the lowest address in each channel and is contiguous until the asymmetric zone begins or until the top address of the channel with the smaller capacity is reached. In this mode, the system runs with one zone of dual-channel mode and one zone of single-channel mode, simultaneously, across the whole memory array.

System Memory Controller Organization Mode (DDR4/5 Only) - 001 - ID:655258 | 12th Generation Intel® Core™ Processors Datasheet, Volume 1 of 2

edc.intel.com

 

[Starjack34]

@Starjack34 In your screenshot CPU-Z shows a DRAM clock of 1596MHz, HWinfo 1330MHz and GPU-Z 2660MHz, weird.

If we take HWinfo clock of 1330MHz that gives a DDR speed of 2660MT/s and with dual channel 128bits (which is 16 Bytes) gives 16 x 2660 = 42,560MB/s or 42.56GB/s maximum theoretical bandwidth. Usually I see about 80% or so of that in real life in optimized benches.

DRAM bandwidth can be checked with Intel mlc

Intel® Memory Latency Checker v3.11

Intel® Memory Latency Checker (Intel® MLC) is a tool used to measure memory latencies and b/w, and how they change with increasing load on the system.

www.intel.com

Or if you prefer to target igpu then poclmembench uses openCL

GitHub - kruzer/poclmembench: calculates your gpu memory speed

calculates your gpu memory speed. Contribute to kruzer/poclmembench development by creating an account on GitHub.

github.com

Example of my dual channel DDR3 @800MHz DRAM clock (1600MT/s)

allocated 1476395008 bytes 1.38 GB
Running Bench test on:Intel(R) HD Graphics 4600
Chunk:   0 (   0- 128)MB Speed: 21.15 GByte/s OK
Chunk:   1 ( 128- 256)MB Speed: 21.28 GByte/s OK
Chunk:   2 ( 256- 384)MB Speed: 21.37 GByte/s OK
Chunk:   3 ( 384- 512)MB Speed: 21.35 GByte/s OK
Chunk:   4 ( 512- 640)MB Speed: 21.31 GByte/s OK
Chunk:   5 ( 640- 768)MB Speed: 21.32 GByte/s OK
Chunk:   6 ( 768- 896)MB Speed: 21.25 GByte/s OK
Chunk:   7 ( 896-1024)MB Speed: 21.31 GByte/s OK
Chunk:   8 (1024-1152)MB Speed: 21.36 GByte/s OK
Chunk:   9 (1152-1280)MB Speed: 21.30 GByte/s OK
Chunk:  10 (1280-1408)MB Speed: 21.31 GByte/s OK

Max theoretical bandwidth would be 25.6GB/s

Both the 8GB and 4GB RAM my system has are similar in speed and technology. They're both DDR4 SDRAM type of RAM with max speed of 3200MHz or 1600MHz each. I was really anticipating that the dual channel would've been that effective especially when you have identical specs of separate of RAM chips, despite the difference of capacity. Unless my system's motherboard has limit certain things including their clock speed which is weird. My current laptop is the most modern one i ever purchased. So modern, the Core i3-1215U processor itself was at least some months old after it was launched. By the end of this October, would be a year after i purchased my device.

 

[W1zzard]

Thanks for testing a private beta @Starjack34. This will be fixed in next release. Underlying reason is that ADL/RPL has two memory controllers. I only checked the bus width on one of them.

 

[Assimilator]

Thanks for testing a private beta @Starjack34. This will be fixed in next release. Underlying reason is that ADL/RPL has two memory controllers. I only checked the bus width on one of them.

You mean RKL, right?

These two memory controllers, are they the ones for DDR4 and DDR5 respectively?

 

[lexluthermiester]

Both the 8GB and 4GB RAM my system has are similar in speed and technology.

All of this having been tested, you should consider buying a matching 8GB stick and swapping it with the 4GB stick so you can get the best from your setup. 8GB sticks of DDR4-3200 are very inexpensive at the moment.

 

[W1zzard]

You mean RKL, right?

OP has a i3-1215U

 

[Assimilator]

OP has a i3-1215U

Derp!

 

[Starjack34]

All of this having been tested, you should consider buying a matching 8GB stick and swapping it with the 4GB stick so you can get the best from your setup. 8GB sticks of DDR4-3200 are very inexpensive at the moment.

I was hoping to get a 8GB stick when my mother went NY last year along with my current laptop i purchased as well, especially since I'm living in Trinidad and things does be somewhat expensive down here. But she end up purchasing two 4GB RAM sticks, one currently use in my device. But since i started back working, i might invest in one not too soon. Probably during the last quarter of this year.

 

[Starjack34]

I have purchased a 8GB RAM stick and is working well in my system.

 

[lexluthermiester]

I have purchased a 8GB RAM stick and is working well in my system.

Heck yeah! Nice! I'll bet things are a bit smoother for you as well.