Western Digital Corp is blaming a defective microprocessor on a fault that can cause its hard drives to fail to power up after six to twelve months of use. On Wednesday, the company warned OEM customers, resellers and retailers of the problem, and said it would be recalling the 6.8GB per platter WD Caviar product lines as a preventative measure. The drives range in capacity from 6.4 to 20.5Gb. It said no customers had reported problems to date. No other WD Caviar drivers, nor Expert, Enterprise or Performer hard drives are affected. The fault showed up as part of the company’s long-term predictive testing program.

Drives manufactured between August 27 and September 24 use the faulty chip. Western Digital said it would recall the 400,000 units sold from the one million manufactured over that time. It wasn’t clear how many of the 400,000 had reached consumers. Compaq said the 4,600 systems shipped in Europe and Asia were affected, while Dell Computer Corp and Apple Computer Corp are thought to have shipped a few thousand each. Replacing the chips in the drives is relatively simple says Western Digital, as the rework involves only the circuit card assembly. The sealed head disk assembly is not affected, it says. A software utility posted on the company’s web site can be used to identify disks at risk.

Earlier this month, Western Digital cited component availability as one of the reasons that its first-quarter results will fall below current Wall Street expectations. It says those component problems are not connected with the recall. Last month, it announced it would cut 2,500 jobs in Singapore, or 60% of its workforce there, in an effort to cut costs. The new setback will cost Western Digital one month’s worth of lost production aside from the recall expenses.