Something quite interesting, and that we will tell you later, is that AMD SAM is not a new technology. Such technology has been around for many years, but has never been implemented before for unknown reasons. But who cares, we already have it available and this means that we have more FPS in the games, which in the end, is what we all want.
What is AMD Smart Access Memory or SAM?
As we said, this technology is based on Resizable BARa solution developed by PCI-SIG and which is a complement to the Above 4G Decoding technology. What AMD has done is to unify these two technologies in the same solution to improve the amount of FPS. In case you had any doubts, AMD SAM is a completely free technology that anyone (if you meet the requirements) can activate it.
Until the implementation of this technology there were major limitations in the communication between the processor and the graphics card. The graphics API, such as DX12, could only send 256 MB blocks to the graphics card memory. This new solution removes this size limitation and can also be done simultaneously. To date, there was not only a limitation on the size of the blocks, there were also limitations on the time of sending. First one block had to be sent and then the next, multiple data blocks could not be sent simultaneously. Additionally, it can be commanded from anywhere in the memory or the processor, as required.
This system requires the implementation of Above 4G Decoding. This feature allows the amount of RAM allocated for the processor to exchange information with the VRAM to be greater. Now we will see a increased consumption of RAM memory of our highest PC with AMD SAM activation. This eliminates the restriction of grouping the information in blocks of 4 GB, something that goes back a long way.
What this solution allows us is to improve performance with high resolution textures. But using this technology requires two additional features. The first is that it is enabled 64-bit PCIe bus decoding, allowing to assign more than 4 GB of information to the VRAM of the graphics card. At the same time, this improves the overall latencysince the number of blocks is reduced.
All this works by what is called as GART either Graphics Address Remapping Table(some call it GTT). This is the unit that is responsible for communicating the VRAM with the system RAM through WFD and with it what is currently called as RAM Diskwhich is nothing more than a space in RAM memory reserved for exchanging textures and data with the graphics card and its memory.
In fact, GART is in charge of sharing the system RAM with the iGPUs of AMD and Intel APUs. The effect in practice is not the same, but the end is similar. What we have to be clear about is that when AMD SAM is activated, space in RAM memory is reserved exclusively for the GPU and its VRAM. In addition, the transfer of information from the processor, which has constant communication with both components, is prioritized. It is also possible to reduce the access time and, consequently, the latency of the system.
Resizable BAR
We have commented that AMD SAM is based on the Resizable BAR technology is a proposal for the PCIe bus that manages PCI-SIG. The interesting thing is that Resizable BAR was proposed in 2008 by HP and precisely by AMD. The controller of the standard, PCI-SIG, I accept and was introduced for the first time in the PCIe 3.0 interface.
PCI-SIG defines Re-Size BAR in the following way:
This optional ECN adds the ability and functions with BAR to report various options regarding the sizes of resources allocated to memory to function properly. Also added is a capability for the software to program the size to configure the BAR.
After this and 8 years in between, the association launched the May 5, 2018 a new review already focused on PCIe 3.x which is quoted like this:
The Resizable BAR Capability currently allows BARs of up to 512GB (239), which allows the address bits <38:0> go to an end point. This proposal extends them up to 263 bits, which supports the full possible address space.
While on August 25, 2016, the latest improvement for this technology was released:
Similar to, and based on, variable-size BAR ECNs (Resizable BAR) and expanded variable-size BAR (Expanded Resizable BAR), this optional ECN adds the ability for PFs to resize their VF BARs. This ECN is written with the expectation that the Expanded Resizable BAR ECN will have been released prior to the release of this ECN. This ECN is compatible with all BAR sizes defined by the Resizable BAR and Expanded Resizable BAR ECN.
Why is all of this important to AMD SAM? Because this technology is based on PCI-SIG’s Resizable Bar, it was picked up by AMD and adapted. They customized and adjusted it according to their criteria and their needs. This means that from the Ryzen 5000 Series and Radeon RX 6000 Series processors, you can use the solution AMD SAM. This eliminates the limitation of information blocks of 256 MB and the consequent fragmentation of the VRAM.
Requirements to activate AMD SAM
As expected, a series of parameters and requirements are needed for SAM to work and to increase the performance of the GPU and therefore offer more FPS. What do we need specifically? According to AMD:
- A base plate 500 series.
- a processor Ryzen 5000 or Ryzen 3000 selected
- (all except the Ryzen 5 3400G and Ryzen 3 3200G)
- A series GPU RX6000.
- driver Radeon 20.11.2 or later.
- Have the motherboard BIOS updated to one based on AGESA 1.1.0.0 or higher.
If we meet these requirements, which is not really difficult at the moment we find ourselves, we can proceed to activate it with a few simple steps that we will see below.
How to activate AMD Smart Access Memory
Those who have a system that meets the requirements should have no problem activating AMD SAM. We simply have to access the BIOS and make some simple adjustments that we are going to explain step by step. These are:
- Apay for the computer
- Press to turn it on and then on the keyboard press DELETE, F2 or F12, depending on the motherboard. If it does not work for you, here we explain other methods to enter the BIOS
- Let’s go to the advanced option, inside the BIOS menu
- First disable the csm-support. Some manufacturers require you to perform this step before displaying the options to activate AMD SAM
- Now we must access the PCI submenu and perform these two actions:
- Above 4G Decoding: We must activate it, so we select enabled
- Re-Size BAR Support: We have to put it on Auto
- Once this is all, we can exit BIOS, saving the changes
If you have doubts about whether it is activated, we can verify it with GPU-Z. This software has a specific section for Resizable BAR and there it will tell us if it is Enabled (activated) or Disabled (deactivated).
Even if we have it activated, it may not have an effect on all games. We must know that we do not have to obtain a performance improvement, even if it is activated. But, the good thing about AMD SAM is that it is not dependent on game support or developers.
