I have a Lenovo W520 laptop with Intel i7-2860QM quad core 2.5GHz processor I want to upgrade from 16 to 32 GB (4 x 8GB) what is the correct memory to buy???

Hello Trent, Thank you for contacting us in regards to your question. Yes, this RAM is correct for your current laptop. Also, you can use 1866 Mhz. Thank you, Newegg Support

Questions & Answers: CMS 16GB (2X8GB) DDR3 10600 1333MHZ NON ECC SODIMM Memory Ram Upgrade Compatible with Lenovo® Thinkpad W520 Quad Core 4270; 4276, 4282, 4284 - A13

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CMS 16GB (2X8GB) DDR3 10600 1333MHZ NON ECC SODIMM Memory Ram Upgrade Compatible with Lenovo® Thinkpad W520 Quad Core 4270; 4276, 4282, 4284 - A13

Computer Memory Solutions guarantees compatibility with models provided in description.
Memory Type: SODIMM, 204-Pin
Speed: DDR3-10600, 1333 MHz
2 Piece Kit
Product appearance may vary. Picture for reference only. limited lifetime warranty when bought directly from computer memory solutions

$60^.00 –