This message was posted on behalf of Intel Corporation
According to the datasheet: Intel® 64 and IA-32 Architectures Software Developer’s Manual
page: Vol.1 5-1, contains the instructions necessary on processor.
The compatible processors with the instructions LAHF / SAHF and PrefetchW with socket LGA 775 are Core 2. Intel already stopped producing them some time ago. Here you have a list of the models available.
Intel® Core™2 Processor