Hoping to upend Apple’s Mac Pro cart, Dell said its new Precision 7500 dual Nehalem Xeon workstations will pack up to six times the amount of RAM and at higher speeds than are available with today’s hottest Apple machines.

Users can get to the 192GB mark by stuffing 12 16GB DIMMs into the Precision T7500’s chassis. Dell said the RAM speeds are also increased thanks to support for DDR3/1333. The Precision will use registered ECC RAM for high density configurations. The new chips will also mark the end of FB-DIMM in the dual processor Xeon lineup.

FB-DIMM’s, which use a small and wickedly hot memory controller on each DIMM to buffer the signals, have long been dinged for massive thermal issues and latency penalties. Dell officials said people’s feelings on FB-DIMM aside, it did get the previous generation of CPUs to the RAM densities people needed. One of the primary justifications for FB-DIMM was the density issue on DDR2 but Dell officials said the 192GB mark for DDR3 was not a major technical hurdle in itself. Keeping it cool and keeping acoustics acceptable was a problem, but Dell said it has it under control.

Bandwidth and compute performance of the dual Nehalems leave the previous design in the dust, Dell said. Like the Core i7, the top-end Nehalem Xeons will feature 8MB of L3 cache, 6.4GT/s QPIs, and support Turbo Mode and Hyper-Threading. The Xeon’s will also support something called Direct Cache Access which lets single-threaded applications subsume all of the available shared L3 cache when it’s not being used by other threads.

For expansion, the Precision T7500 will feature five physical x16 PCI-E 2.0 slots. Two will run at x16, two at x8 and one at x4. An additional PCI-X and PCI will be included for legacy hardware. Dell will support Windows XP and Vista in 32-bit and 64-bit flavors as well as Red Hat Enterprise Linux in 64-bit, FreeDOS and Novel SLED Linux.

Oddly, Dell didn’t release the clock speeds nor model numbers of the CPUs in the launch but it is assumed that the company will use Intel’s 2.93GHz Xeon X5570 part. Apple announced a Mac Pro using the X5570 part on March 3. Dell could also step it up a notch and use the Xeon version of the Intel’s Core i7-965 Extreme Edition brother: the 3.2GHz Xeon W5580. Although Dell and Intel declined to give details on the Xeon lineup, the leaked list has been available for some time. No fewer than ten Nehalem-based Xeon’s are due this year including half-cache versions and even non-Hyper-Threaded and dual-core chips using DDR3/800.

The company said the year marks the ninth year that it has led in workstation machines and current estimates give Dell about 40 percent of the market.