The GPU acceleration in RELION-2 is entirely based on CUDA, which means you need a reasonably modern NVIDIA GPU (Compute capability 3.5 for the experts). You will also need a decent amount of memory on the card – say 4GB or more. RELION-GPU will use most memory during the final autorefinement, and since this always involves two models that can be put on different cards it is often a better idea to get two mid-range cards instead of a single high-end one, if you need to choose.
You also have a choice between professional “Tesla” cards and cheaper consumer “GeForce GTX” that target slightly different audiences. The professional cards have outstanding quality, they have been burnt in by the vendor, they have more memory, and they also provide very good performance for double precision floating point calculations (which is important for many scientific domains). For many rack-mounted servers these cards are the only option due to the way the cooling works and how the power cables are connected. Most compute centers love these cards – one reason is that they will always get a replacement instantly even if the card fails after several years, and the drivers are often more conservative. However… You will have pay a bit for this quality. The advantage is that you will get a card that is certified for your specific server and great support both when you buy and later. For this reason there simply isn’t a whole lot of need to document this – just ask your vendor!
However, the other alternative is consumer hardware. You will not get as much official support here, which means it is useful to document. These cards are not lower quality, but they only provide good single precision performance, they do not have as much memory, and since both hardware and drivers are targeted for a different market (games) you need to burn in new cards yourself. There are only a few rack-mounted servers that accept consumer cards (we’ll describe it in a later post), but the upside is that the cost is only a small fraction. The good news is that we have optimized RELION so you can use consumer cards if you want to – in particular the new 1070 & 1080 cards are outstanding value for money, but stay away from overclocked cards. Those work fine for games that only run at full speed for fractions of a second, but when using the GPU at 100% 24/7/365 and putting several cards next to each other we have had problems. For instance, “game edition” cards that pull in the air sideways will never work in a cluster node! Don’t be too cheap – spend the extra $100 for the “Founder’s Edition” reference models and be fine. We’ll start by showing you the low-end options for desktops and gradually move up.