Fujitsu will upgrade its line of laptop disk drives in May with a new series offering 400GB and 500GB storage.

The company said its upcoming MHZ2 BT series of 2.5in SATA disks will spin at speeds of up to 4,200rpm but crucially will run quieter than the company's older equivalents.

Joel Hagberg, vice president of marketing and business development, said that talks with PC notebook designers and set-top box manufacturers had revealed acoustics to be their main hard-drive bugbear.

"The hum of the drives and fans is distracting," he said. But the MHZ2 disk drive "runs cool enough that it doesn't need a fan."

The new series uses a three-platter design and also offers improved power efficiency over Fujitsu's previous 2.5in SATA disks of 160GB, 200GB and 300GB. It can be installed in desktop PCs, laptops, and media set-top boxes, Hagenberg said.

Fujitsi has yet to release prices for the new drives. However, it has allowed some set-top box providers to perform early tests on them for possible inclusion in future product roll-outs.