Does anyone know why there's a ten-fold difference between peak and sustained power? I would have thought it'd be more like 50%, but I don't work with HPCs.
The performance is measured with LinPack which mostly does FP operations and is optimized to run on the architecture, when normal programs are run, it is tough to run them at full utilization, this is because, a lot of time might be spent in data transfer or I/O apart from the computation ... there would be various other factors !
Also, with GPUs, because of the additional compute power on the server, the network quickly becomes a bottleneck.