SOMETHING strange is happening to the market for tech stocks in the US. For the first time since the great technology investment bubble went phut in 2000, investors are starting to bid some stocks up again into nose-bleed territory.

The hottest demand is not for established industry leaders like Microsoft, Intel, IBM or Cisco. Their share prices are certainly up, typically boosted by hard evidence of improving fortunes. For instance, chipmaker Intel last week forecast higher-than-expected sales going forward. Demand for some of its PC chips is so strong that supply lines are becoming stretched and customers are being put on allocation.

However, the tech majors' share price gains over the past year - Microsoft up by a fifth, IBM 50% higher, Intel more than doubled - are modest when compared with what is happening elsewhere in the sector.

California-based contract manufacturer Sanmina-SCI, which took over IBM hardware assembly operations at Greenock and elsewhere, has seen its share price grow five-fold. Telecoms groups Nortel Networks and Avaya, and fibre optic maker Corning have all seen their share prices increase seven-fold in the past year.

While Microsoft and IBM continue to trade on relatively modest price/earnings ratios in the high teens and low twenties, these second-line tech stocks are back trading at 50, 60 or even 70 times anticipated annual earnings. This new rush to buy into tech companies, some of which still have little to show by way of earnings and no intention of paying dividends, is prompting warnings that another speculative investment bubble is already in the making.

Demand has not yet pushed prices anywhere near the stratospheric valuations that so capti-

vated the bulls three years ago, just before that bubble burst. Corning stock, for instance, is currently trading above $8 a share, compared with the dizzy peak of $113.10 reached in September 2000. And you can still buy into Lucent, another company winning investor attention, for less than $2 a share. In 1999 Lucent stock peaked at just under $84.

However, the renewed interest in the sector so soon after one of the most dramatic share price collapses in investment history prompts some deeper questions about what is going on. Arguably, the biggest question of all is: why start taking these investment risks again when the strategic outlook for the newer technologies remains so clouded in debate and doubt?

Such are the shockwaves from the earthquake that hit these sectors in 2000, that you can't even get the leaders of the IT and telecoms sectors to agree on what happens next. Some predict massive corporate consolidation, akin to the rationalisation that hit the railroads and the car industry when they matured.

Some fret about how to tame the frustrating complexities of the monster they have already created. Many fear our appetite for new gizmos is sated, that the resultant modest demand will severely curtail capacity for business growth. Everywhere you hear the same unanswered question: where is the next big thing coming from, and what will it look like when it arrives?

Bill Gates of Microsoft is on record that there's no going back to the IT spending levels of the late 1990s. Larry Ellison of Oracle claims the Silicon Valley of old, awash with venture capital, creating a promising new company every single day, is gone for good. At the last Davos summit, Bill Joy of Sun Microsystems wondered out loud whether more and more of us already possess every silicon-driven device we could possibly require.

There is even an apocalyptic view, articulated by Nick Carr in the May issue of the Harvard Business Review, that the more pervasive the fruits of IT become, the faster the value it can deliver - in terms of competitive advantage to this company compared to that one - diminishes. IT can do a lot, he argues, but as it rolls out through entire industries, it's not at all clear that companies can effectively differentiate themselves by the ways in which they exploit it.

The magazine BusinessWeek devoted an entire issue recently to the future of technology. It asked ''techdom's heaviest hitters'' what the future held. Reading the responses, one is struck by just how deeply the recent dot.com and telecoms busts have eaten into the brash confidence that once characterised this ageing silicon brat pack.

All the talk of killer apps and exponential growth in demand has given way to much more measured, chastened reflection. In that reassessment, consensus has evaporated. Sam Palmisano of IBM insists the US still has an unmatched IT ecosystem. Masayoshi Son of Softbank counters that the US has to wake up, that the average speed of broadband in America is currently one-twentieth of the installed speed in Japan.

There is still talk of new tech doors opening - bio-informatics, wireless computing and photonics - but no certainty. It hardly seems like a time in the evolution of technology when investors should be piling back in to the survivors of that last great rout.