Intel has relaxed its recall of the faulty Sandy Bridge chipsets, allowing PC and motherboard makers to continue to sell the flawed components under certain circumstances.

The chip giant says OEMs can continue to sell the flawed B2 revision of the Cougar Point chipset - which is used to power the new generation of Sandy Bridge processors - but only if they disable the faulty SATA ports.

The Cougar Point flaw only affects Intel-controlled 3Gb/s SATA ports - the 6Gb/s ports remain perfectly operational. PC makers who only make use of the 6Gb/s ports are therefore being encouraged to carry on regardless.

"If you're a laptop maker, you will find laptops that only need two [6Gb/s] SATA ports for a hard disk and DVD drive," an Intel spokesman told PC Pro. "In these cases, it's perfectly OK to use the B2 stepping."

The spokesman claimed many all-in-one PC and nettop makers would be equally unaffected by the SATA port issue. "We'll let desktop manufacturers go if they fulfill our requirements, which is physically disabling ports two through five," the spokesman added. The 6Gb/s SATA ports are typically on ports zero and one.

Quality controls

Intel admits it's effectively powerless to prevent PC and motherboard manufacturers from selling the flawed B2 chipsets, even if they don't disable the necessary ports. And given that the fault may not become apparent for many months, if not years, there remains a risk that manufacturers will attempt to cash in on their existing stock of B2 chipsets rather than proceed with the rigmarole of Intel's recall or wait for fresh stock.

"We strongly recommend them not do it," said Intel's spokesman, who conceded that customers would have no obvious way of telling whether they have a flawed B2 chipset or not, when the new chipsets go back on sale at the end of this month.

The Intel spokesman did say that the company was "looking into the feasibility of providing a tool that will tell you what chipset you have in your system," so that customers could be 100% certain whether they had an affected part.

Intel denies it's been forced into putting the flawed chipsets back on the market by PC manufacturers who are anxious not to miss out on sales of Sandy Bridge systems. "I wouldn't say we've been under pressure," said the Intel spokesman. "We discovered the problem, saw it needed talking through with customers, and found a resolution."

Faulty transistor

Intel has also provided further technical detail of what caused the problem with the Cougar Point chipsets.

The company says it deployed the wrong type of transistor on the 3Gb/s port controllers. The spokesman said the company uses two different types of transistors on the port controllers: one that is used to drive a long chain of transistors and is required to cope with high currents; and another that doesn't drive a lot of current but is required to switch very quickly.

"We used a transistor that should not have been there - it was not tailored for the purpose it should fulfill," said the Intel spokesman.

The spokesman added that reports of the SATA port performance dwindling over time were incorrect - the affected ports would either work normally or fail completely.