AMD Smart Access Memory Can Work with First-Gen Ryzen CPUs

We previously reported on a rumor suggesting that AMD’s new Smart Access Memory (SAM) feature would only work with Ryzen 5000 Series processors due to the way older chips handled a particular instruction (PDEP), but it turns out that isn’t the case at all. Following an official response from AMD confirming that SAM doesn’t depend on PDED, an ASUS B450-PLUS motherboard user has discovered that the feature can be enabled with an AMD Ryzen 7 1700 processor.

Got a response from AMD about PDEP and SAM:

‘Smart Access Memory does not depend on the performance of the PDEP instruction.’

The speculation about accelerated PDEP on Zen3 being a factor seems to not be the case.

— 𝐷𝑟. 𝐼𝑎𝑛 𝐶𝑢𝑡𝑟𝑒𝑠𝑠 (@IanCutress) December 11, 2020

All you need is the 2409 BIOS update, but unfortunately, benchmarks with the AMD Radeon RX 580 are showing that SAM isn’t making much of a difference in titles such as Shadow of the Tomb Raider and DOOM Eternal. Here are the results for the latter, courtesy of Wccftech:

AMD SAM Disabled:

• Run 1: Average FPS: 125.6 FPS | Min. FPS: 82.2 FPS | Max. FPS: 250.3 FPS | 1% Low: 83.6 FPS | 0.1% Low: 41.1 FPS
• Run 2: Average FPS: 123.0 FPS | Min. FPS: 87.4 FPS | Max. FPS: 251.1 FPS | 1% Low: 86.1 FPS | 0.1% Low: 75.7 FPS
• Run 3: Average FPS: 123.0 FPS | Min. FPS: 87.7 FPS | Max. FPS: 251.4 FPS | 1% Low: 83.6FPS | 0.1% Low: 73.5 FPS

AMD SAM Enabled:

• Run 1: Average FPS: 125.9 FPS | Min. FPS: 85.4 FPS | Max. FPS: 253.0 FPS | 1% Low: 86.0 FPS | 0.1% Low: 77.1 FPS
• Run 2: Average FPS: 124.2 FPS | Min. FPS: 82.0 FPS | Max. FPS: 252.9 FPS | 1% Low: 85.9 FPS | 0.1% Low: 43.0 FPS
• Run 3: Average FPS: 124.6 FPS | Min. FPS: 79.4 FPS | Max. FPS: 252.8 FPS | 1% Low: 81.7 FPS | 0.1% Low: 65.7 FPS

Overall Average with AMD SAM Enabled:

• Average FPS: 124.90 FPS | Min. FPS: 82.26 FPS | Max. FPS: 252.90 FPS | 1% Low: 84.53 FPS | 0.1% Low: 61.93 FPS

Final Results:

• Average FPS: +0.839%;
• Min. FPS: -6.20%;
• Max. FPS: +0.596%;
• 1% Low: +0.119%;
• 0.1% Low: -2.365%

“As you can see, most of the differences are within the margin of error while the minimum FPS take a huge hit which indicates performance degradation with AMD Smart Access Memory enabled on an older generation graphics card,” the author notes.