Czech online retailers claim they’re running out of graphic cards, not because of hot new video games but because of the Bitcoin craze. Special graphics cards are needed for mining cryptocurrencies like Bitcoin and others and the recent spike in the real world value of Bitcoin has emptied the virtual shelves of Czech online retailers like Alza.cz and Heureka.cz. Demand has risen several hundred percent, according to the daily Hospodářské noviny, with prices rising nearly 20 percent. “From the beginning of this year, we’ve seen interest in graphic cards rise 300 percent,” said an official from Heureka.cz. The country’s biggest e-shop, Alza.cz, claims that demand is up 700 percent. “Thanks to cryptocurrency mining, supplies of graphic cards has become a problem worldwide. There are currently 300 locations in the Czech Republic that accept payment in Bitcoin.