1. There are very few analytic DBMSes which are actually fast (and compare against reasonable baselines). Most claims of speed are bogus. Or rather, might be better than what's otherwise available to use, but are still slow.
2. Designing an analytic DBMS to properly utilize a massively-parallel processing device is a monumental task, and I would claim that it has not yet been undertaken. Existing research and production systems graft such use onto a system whose fundamental design dates back to the 1980s in many ways.
3. CPU-utilizing anallytic DBMSes are typically faster than GPU-based ones, to a great extent due to the above - but also since we've had decades of work on optimizing them.
4. GPUs are artificially handicapped on Intel-architecture systems, because they are placed "far" from main memory relative to the CPU. More literally - the bandwidth you get t between your GPU and main memory is typically 0.25x the bandwidth a CPU socket has with main memory. This is critical for analytic query processing (as opposed to neural network simulation which is more computation-heavy and can tolerate this handicap much better).
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PS - Always glad to discuss this further with whoever is interested.