Can’t upgrade laptop RAM

I bought a second-hand Toshiba Satellite c660 laptop for $150. It came with 3GB and I’ve tried upgrading it to 8GB RAM using Crucial’s website to guide me to a purchase on eBay. But on installing it I get a blue screen “Kernel security check failure” error. A local shop also tried installing RAM and updating the BIOS but got the same error. I’m now at a loss as to what I can do – any suggestions? PETER BLACHFORD

We first advised Peter on upgrading to an SSD drive to improve performance, which would also give him the opportunity to see if installing a fresh copy of Windows with the 8GB fitted would work, but sadly the same error message came up before anything was written to the drive. Older Toshiba Satellite laptops have a bad reputation for being sticklers about RAM – many users have reported success with adding a single stick of 4GB to the current 2GB stick, so Peter might like to try this to see if he can bump things up to 6GB. Otherwise it may be a case of entering the BIOS to see if he can find and write down the memory timing settings for the original 3GB sticks, then fit the new RAM (which is recognised correctly in the BIOS) and compare its memory timings – if necessary, alter these to match the original RAM. If Peter can get at least 6GB RAM working, then clone his Windows installation to his new SSD drive, he should see a significant improvement in performance. ALEX COX

OLDER TOSHIBA SATELLITE LAPTOPS HAVE A BAD REPUTATION FOR BEING STICKLERS ABOUT RAM – MANY USERS HAVE REPORTED SUCCESS WITH ADDING A SINGLE STICK OF 4GB TO THE CURRENT 2GB STICK.