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This CPU has no marking or laser etching on the heatsink so the sSpec number and production date remain unknown. To identify this chip I've tested it in my LGA775 motherboards and found out that it would only run in my Gigabyte P35-DS3 Rev1.0. Motherboards like ASUS P5P800SE, ASRock 775Dual-VSTA and some Intel engineering sample boards (both desktop and server) didn't boot using this CPU.

Using the Gigabyte P35-DS3 I was able to run this CPU but I had to disable 'No Execute Memory Protect' in the BIOS in order to boot Windows XP correctly. I also noticed that the vCore is set automatically on 1.556 (if I set 1.475V it'll read 1.428V so the actual configured voltage is probably higher than 1.556V!) volts which is quite high. Due to the high voltage the CPU runs quite hot. My watercooling setup is able to keep it below 60C (stressed) which is just low enough for benchmarking. If it hit's higher temperatures it'll crash.

To identify the CPU I used CPU-z. It turned out to be a Xeon 'Irwindale' 90nm CPU with 2MB L2-cache which is the Xeon equivalent of the Pentium 4 'Prescott-2M'. 'Irwindale' is the successor of 'Nocona' and has 1MB L2-cache more and is able to do speedstep. 'Nocona' is the equivelant of the Pentium 4 'Prescott'. The Gigabyte P35-DS3 motherboard detects CPUID 0F4A with Patch ID 0000. I think the CPU doesn't have a fixed CPU-string so it will always show 'Genuine Intel(R) CPU x.xxGHz' which may vary depending on the clock frequency. If I overclock it to 3.8GHz (which is doable, 3.9GHz is difficult) it will P.O.S.T. as 3.8GHz CPU. CPU-z identifies a 'Genuine Intel(R) CPU 6.00GHz (ES)' and I suspect this has something to do with the multiplier which is detected as fully unlocked. A multiplier of 60 with the lowest base/system clock possible will result in 6GHz. Despite the multiplier is detected as fully unlocked I can not use multiplier 21x or higher. Also note the 266MHz (QDR1066) front-side-bus; this is the only Xeon 'Irwindale' I've seen using that FSB-clockfrequency. Others have 200MHz (QDR800).

The Irwindale R0-core was introduced in November 2005 so this CPU is probably a bit older. The first rumor about the Irwindale I could find dates back to November 2004. > Read more