Newer Technology demonstrated the iMAXpowr G4 433 upgrade for iMac at Macworld Expo, New York, yesterday.

The upgrade has a 433Mhz G4 processor, with 1MB backside cache running on a 216MHz cache bus. It costs $549 - UK pricing is not yet available.

Like previous iMac upgrades from Newer, the user must return the original processor to the company in order to qualify for a $150 rebate - the upgrade costs $699 otherwise.

iMAXpowr G4 433 is compatible with the first versions of the iMac, and runs on OS 9 or better - no additional software is required.

System performance is almost doubled by the upgrade, according to the company. MacBench returns a CPU score of 1380 for an iMac with the upgrade, a Rev A iMac without scored 721. It began shipping in the US today, and is expected to ship the UK in the next few weeks.

Newer also announced the MAXpowr G3-PB 466 for Wallstreet and Bronze PowerBooks. The 466MHz upgrade costs either $499 or $549, depending on the type of cache (Ball Grid Array or Thin Quad Flat Pack) used in the original machine. The upgrades will ship in late August 2000.

The PowerBook upgrade is complex and users must first remove their CPU and despatch it to Newer. The company will then rebuild the CPU, and add a faster microprocessor. The process takes five days, and is "not trivial".