The US personal computer market should slow down during the third quarter due to seasonal factors and high inventory levels at distributors, market researcher Dataquest Inc said in a report issued yesterday, Lori Valigra reports from Boston. However the research house said that the market did not slow down as expected in the second quarter as expected, and indeed US shipments rose 23% over the same quarter last year. Dataquest has been forecasting 16% growth for the US for this year, down from 20% in 1993. Compaq Computer Corp, which overtook IBM Corp in the first quarter to become the top personal computer seller, widened its lead in the second quarter, when it shipped almost 130,000 more personal computers in the second quarter than its nearest competitor, which was Apple Computer Inc. Apple moved ahead of Packard Bell Electronics Corp because of strong PowerBook sales, but Power Mac sales were lower than expected, Dataquest said. Compaq had 13.4% of the market, followed by Apple with 10.8% and Packard Bell with 9.9%. IBM stayed in fourth place but because the company has been buying back some products from distributors, Dataquest restated first quarter shipments, cutting the US shipment figure of 398,000 recorded earlier to 309,000 after IBM took back old products from the distribution channel.Dataquest said Digital Equipment Corp surpassed Gateway 2000 Inc in the second quarter to rank10th in worldwide personal computer shipments.