The Irwindale processors are a variant of the current Nocona Xeon DPs, and both support 64-bit memory extensions that are compatible with (and very likely derived directly from, thanks to the wonders of patent cross-licensing agreements) the 64-bit memory extensions in the Opteron processors from AMD.

The Irwindales have 2MB of L2 cache memory on chip, compared to 1MB on the Noconas, and Intel benchmarks have suggested that performance of the Irwindales can be as much as 18% higher than for the Noconas, clock for clock. The Irwindale chip has an 800 MHz frontside bus, just like the Nocona chip, which means it can plug into the exact same slots. The Irwindales are, like the Noconas, available in 2.8GHz, 3GHz, 3.2GHz, 3.4GHz, and 3.6GHz variants.

Considering that AMD today cut prices of its own Opteron processors–the ones that compete directly with the Noconas and Irwindales and at essentially the same price points–by 35% to match Intel’s Nocona prices at roughly the same performance level, it would have been a safe bet that Intel was going to have to cut its Nocona prices a little or not be able to charge more than a slight premium for Irwindales.

As it turns out, Intel is charging the same prices for Irwindales as it used to charge for Noconas, ranging from $259 for a 2.8GHz chip to $851 for a 3.6GHz chip (prices are, as always, for 1,000-unit quantities).

The Irwindale chips not only have a larger L2 cache, but they also include the new Demand Based Switching (DBS) and SpeedStep power management features that Intel perfected in its laptop processors and the Execute Disable (XD) security enhancement.

The DBS and SpeedStep features of the Irwindales senses how much load is on the processors, and if applications are not consuming a lot of CPU cycles, they scale back the clock speed and voltage of the processors to meet the processing needs of the workload. By cutting back cycles and volts, a server can consume 24% power as workloads decrease.

In racks or blade chassis full of servers, this is a big savings in power consumption. The XD feature is Intel’s name for the No Execute (NX) hardware feature that first appeared in AMD’s Opteron processors. Both NX and XD mark certain areas of main memory as non-executable, which helps servers resist attacks using buffer overflow techniques.

Aside from chopping prices on its Opteron 100, 200, and 800 Series of chips, AMD this week is rolling out a faster Opteron that runs at 2.6GHz and that includes a faster 1GHz HyperTransport connection to other processors in a NUMA cluster. The current Opterons, which are based on 130 nanometer copper processes, have 800 MHz HyperTransport links.

The new Opteron 152 (for uniprocessor machines), Opteron 252 (for two-way machines, and directly competing with Nocona and Irwindale), and Opteron 852 (for four-way and larger systems) are implemented in a 90 nanometer process, which allows their clock speeds and HyperTransport speeds to be ramped up. AMD has left the L2 cache size at 1MB in the Opterons, since its architecture is focused more on memory bandwidth than cache bandwidth.

The new Opterons also include support for Intel’s SSE3 instructions, which speed up media processing. AMD is also announcing a new I/O chip, the AMD-8132 HyperTransport PCI-X 2.0 tunnel, which it says will ship in servers and workstations later this month. The AMD-8132 is an adjunct chip to the AMD-8000 chipset, and allows PCI-X peripherals to link into the HyperTransport buses.

All Opterons shipped since last summer have AMD’s PowerNow power management features, so it is already ahead of Intel on this front and it did not need to add these features to the new Opterons. Like other Opterons, the new 152, 252, and 852 processors have a peak heat dissipation of 95 watts.

AMD also ships Opteron HE variants of its standard Opteron chips that run at a lower voltage and pump out only 55 watts, and the company sorts through its bins to find Opteron chips that can run at even lower voltage to dissipate a peak 30 watts, and calls them the Opteron EE. AMD is charging a premium for these Opteron HE and Opteron EE chips, and will later this year deliver such variants of the new Opteron 152, 252, and 852 processors.

AMD says that the Opteron 252 and 852 processors will begin shipping to server and workstation partners within 30 days, and that volume shipments of servers based on these chips are due before the end of the first quarter. The Opteron 852 costs $1,514 in 1,000-unit quantities, while the Opteron 252 costs $851 for the same tray sizes. AMD says that the Opteron 152 will be available on April 30 and will cost $637 for 1,000-unit quantities.