Adds details from results Aug 24 (Reuters) - Chip designer Nvidia Corp NVDA.O predicted third-quarter revenue below market expectations on Wednesday after weak gaming demand led to a 19% sequential decline in second-quarter sales. The gaming industry is showing signs of weakness as consumers pull back from discretionary purchases such as video-gaming gear amid decades-high inflation. Chipmakers have also been struggling with supply-chain snarls ahead of the key holiday period due to the Russia-Ukraine conflict and COVID-19 curbs in China's manufacturing hubs.