I have gotten a 2nd hand i7-870 and after testing it with CPU-Z and Task Manager, it shows 2 core 4 threads.
The person who sold it to me mentioned that it pulled it out from Lenovo ThinkCentre A85 (Link -> https://support.lenovo.com/sg/en/documents/pd014443 Detailed specifications - ThinkCentre A85 (type 0104, 0154, 7539, 7548) - Lenovo Support (SG)).
And from the website it indeed shows Intel® Core i7-870 2.93G 1333MHz 4T\Dual core\8MB cache.
Is this true? Is the processor really a 2 core 4 threads one instead of 4 core 8 threads?'
Some facts and testing I have done:
According to http://ark.intel.com/products/41315/Intel-Core-i7-870-Processor-8M-Cache-2_93-GHz Intel® Core™ i7-870 Processor (8M Cache, 2.93 GHz) Specifications you should have 4 cores and 8 threads. Have you checked if all the cores are enabled in your BIOS configuration? You can run the https://downloadcenter.intel.com/download/19792/Intel-Processor-Diagnostic-Tool Download Intel® Processor Diagnostic Tool to check if are enabled or disabled, but in order enable them you need to enter your BIOS configuration.