Hard-disk drive maker Seagate (STX) jumped 21.8% to $29.35 on strong preliminary resultsSeagate Technology Plc estimated fourth-quarter revenue higher than Wall Street expectations, helped by strong demand for hard-disk drives.The company estimated revenue of about $2.65 billion for the quarter ended July 1, above analysts' expectations of $2.33 billion.The company also said it would cut about 6,500 jobs, or 14% of its global workforce, by the end of fiscal 2017. The total pretax charges for the restructuring plan will be about $164 million in the current fiscal year, the company said on Monday.Seagate, which has more than 52,000 employees worldwide, said in June that it would cut 1,600 jobs as the company looks to rein in costs amid waning demand.The company also said it expects adjusted gross margin of about 25.8% for the fourth quarter, up from its previous estimate of about 23%.According to research firm International Data Corp, worldwide PC shipments fell 4.5% to 62.4 million in the second quarter. IDC had expected a fall of 7.4%.Seagate will report is fourth-quarter results on Aug. 2.Numbers are good, cost cutting is also a right thing, but I am worried about declining PC shipments. I am afraid this factor will be very hard to address. Personally, I will stay out of this stock at the moment, but if PC shipments reverse STX will be my top pick in the sector. $STX, Seagate Technology Holdings PLC / 1440