Dell notebooks with solid-state drives are being returned by unhappy customers at a very high rate, as buyers find that the pricey mobile PCs fail to perform at a level that justifies the additional cost for the hard-disk drive alternative, an analyst said.

Computer vendors have been marketing SSDs as more reliable, durable, and faster than traditional HDDs. But Avi Cohen, managing partner of Avian Securities, said in a recent report that he found the rate of return on SSD notebooks from one major manufacturer ranges from 20% to 30%. Dell on Tuesday confirmed that it was the manufacturer named in the report.

Cohen told InformationWeek Tuesday that within a PC environment, where data in many formats is being written and read constantly on the storage device, SSDs have not performed as advertised in comparison to HDDs. "We're seeing high return levels, high failure rates, and no performance advantage," Cohen said. "There's actually a performance disadvantage over regular drives."

While SSDs can add some battery life to a notebook, that doesn't come close to justifying the cost. A 64-GB SSD from Dell, for example, runs as high as $1,149, while a 320-GB mobile hard drive from Western Digital is priced at $170.

SSDs perform better than HDDs in environments when data is written once to the device and read many times. But SSDs fail to provide a better overall experience. "People are very disappointed," Cohen said. "It's the total user experience that's at fault here."

A Dell spokesman said Cohen's findings were not even close to Dell's own numbers. "What was reported by Avian Securities is wholly inaccurate by orders of magnitude," he said. Dell would not provide specific numbers.

Cohen also found that the rate of return because of technical problems with SSD notebooks was running 10% to 20%, compared with 1% to 2% for mobile PCs with HDDs.

The poor performance of SSDs isn't surprising, given the relative infancy of the technology with notebooks, Cohen said. The performance of the drives is sure to improve in time. "This isn't something that's permanent," he said. "It's just a matter of time before someone figures this out."

The price is also expected to come down as manufacturers switch to multilevel cell drives for notebooks instead of the current single-level cell drives. The latter drives store 1 bit of data in each cell, while multilevel cell drives store 3 or more bits in each cell. The latter have slower transfer speeds and higher power consumption, but are far less expensive to make.

Cohen expects to see improvements in price and in the technology next year. That, however, is not going to help SSD manufacturers that are "sucking wind" this year and are hoping notebook sales "would get them out of the hole they're in," Cohen said.

NAND flash is the memory technology used in SSDs. Researcher iSuppli last month cut its 2008 revenue outlook for the global NAND flash market to the single-digit percentage range from its previous estimate of a 27% increase. Flash manufacturers last year took in $13.9 billion.

ISuppli issued the warning "amid troubling signs of order reductions and weakness in consumer spending."