Just to vouch (in case it's still necessary), got my a4, all good and working fine.
Just a tip, try running the fan at 100% for a few minutes, it unloads big chunks of dust.
Thanks for the business my friend, good luck for the rest of your sales
just a suggestion assuming the factory warranty is gone, might be a good idea to actually clean the heatsinks and fan blades on any used miner from anyone before operation ,it will greatly prolong life and keep temps cooler longer, I wouldnt think fan speed alone will fully clean it
an old toothbrush works wonders for sinks and blades