By Katie Marsal

Published: 01:00 PM EST

Apple this week is advising members of its reseller channels that supply of iMacs will be constrained in the immediate future, a move that may signal new models are nearing production.

In particular, people familiar with the matter say the Cupertino-based Mac maker has warned that new reseller orders for the high-end 24-inch 3.06GHz iMac are unlikely to be fulfilled, suggesting manufacturing of that model is ramping down or has already ceased.

Additionally, Apple is said to have braced its partners for limited availability of the remainder of the iMac line in the coming weeks, a sign which this late in the product's life-cycle "only means one thing" -- namely that the company is drawing down inventory levels ahead of new models.

So far, details on the next-generation of iMacs are few and far between. Outside inadvertent confirmation on Apple's part that the systems will employ chipsets from NVIDIA Corp., the remainder of their hardware makeup remains unclear.

A recent analyst report had speculated based on source information that Apple was still facing a dilemma of whether to advance the all-in-one desktops to quad-core systems or continue using Intel's mobile Core 2 Duo chips. Given that production of current models is now believed to be winding down, it's almost a certainty that the company has made its decision.

Supporting a possible move to quad-core processors in the iMac line was a November report from Taiwanese rumor site DigiTimes, which claimed that Apple was among a list of PC makers who had agreed to adopt Intel's new quad-core 65W low-power desktop processors that range in speeds from 2.33GHz to 2.83GHz.

The report did not specify in which models Mac maker would employ the parts, however. But short of Apple introducing a completely new breed of Mac desktop, it would appear the only likely candidates for such chips would be the iMac and Mac mini, with the former being a safer bet from both a strategic and historic standpoint.

Assuming the report remains accurate, it would bode with similar rumblings AppleInsider has heard about the direction in which Apple plans to take its flagship desktop line during the 2009 calendar year. With Mac OS X 10.6 Snow Leopard set to debut with Grand Central technology aimed at leveraging Macs with an increasing number of processor cores, it's safe to assume that the majority of the company's Mac offerings will soon see a bump from dual-core to quad-core.

Also fueling rumors of iMac revisions due this quarter were a couple of independent reports out of the Chinese-language Economic Daily News. The first, published in late December, cited sources as saying Apple was scheduled to "launch a new iMac all-in-one PC in the first quarter of next year, and the company's sole manufacturing partner, Quanta Computer, is gearing up to supply monthly shipments of around 800,000 units during the first quarter of 2009."

The second report, filed less than a week later, sparked speculation that the next-generation models would employ a new cooling system than the current iMacs when it identified two OEMs -- Foxconn Precision Components and Auras Technology -- as the team that would manufacturer "the PC's cooling module" without offering details on any of the system's other components. Outside of that report, there's been no concrete evidence to suggest a change to the iMac's cooling methods.

It should be noted that should the iMacs adopt the Intel chips singled out by DigiTimes, it would mark a significant architectural shift for the desktop line, which has long relied on the same breed of mobile chips found in Apple's MacBook and MacBook Pro lines. The quad-core chips in question are true desktop-oriented processors with a higher thermal design point.