If you need a compact platform for PhotoScan, or want the most cost-effective option (performance per dollar, rather than absolute highest performance) this compact dual GPU system is ideal. We have found that the Build Dense Point Cloud step in PhotoScan is by far the longest and most demanding part of this software, making up 50 to 90% of the overall runtime. This step is also heavily GPU accelerated, and for that reason we have focused our designs on multiple video cards to improve overall performance.
In addition to this GPU-centric approach, this design also offers multiple drive options and fairly high RAM capacities in order to suit the needs of a variety of users. We recommend a SSD for the OS / application, another SSD for your active images / projects, and then a large hard drive for storage. The amount of RAM needed will depend on the number and size of images in your data set, and what quality settings are being used. Here is a chart from Agisoft showing their memory recommendations.