Non-SLI GPUs in NAMD

From: Raman Preet Singh (ramanpreetsingh_at_hotmail.com)
Date: Thu Jun 04 2020 - 12:56:58 CDT

Dear All,

I am looking towards building a cheap computer for MD using cheap and second-hand components. The systems that I am interested in studying are typically below 25K atoms so there is no need for very large number of compute cores.

In one such consumer desktop, I could get performance close to 40 ns/day using a consumer GPU 1050 Ti. However, when I tried attaching another 1050 Ti (motherboard has 3 PCI slots), it was not detected by NAMD. The OS, 64-bit Win 10, too showed issues with one of the two GPUs. Reading through loads of forums and tech documents I found that the said motherboard detects more than 1 GPU only if the GPUs support SLI. 1050 Ti is a non-SLI GPU.

When I tried these two GPUs in a motherboard used for cryptocurrency mining, the OS (64-bit Win 10) and NAMD were able to detect the two GPUs. As expected, these were identified as device 0 and 1 by NAMD. However, I could not confirm performance gain as the processor was a low throughput one and apparently 1 GPU was enough to obtain the maximum performance.

Reading through several websites, I found that SLI combines the performance of multiple GPUs to produce a single output. Cryptocurrency algorithms break the job in multiple instances and each instance is run individually on a GPU and the output of all the GPUs is then combined hence, non-SLI GPUs work independently in a mining rig. While searching for GPU support in NAMD, I could not find any specific reference to SLI or non-SLI cards.

My questions are:

  1. Does NAMD support multiple non-SLI GPUs?
  2. Can two or three non-SLI consumer GPUs (1050 Ti), when included in a mining rig with 8/16-core processor, be used for performance improvement of NAMD?

Regards,
Raman

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