Memory upgrade- getting conflicting Info

MacBook Pro, 2.53 GHz, i5, 1066 MHz, DDR3. I recently upgrade OS from Snow Leopard to Maverick. Ordered 8Gb memory chip to replace the two 2 GB chips in the system. Am told by major vendor (Memoryten) that one 8 Gb can be added to one of the two Gb slots for a total of 10. Also being told by Apple tech guy that's not true, that I can only add two 4 Gb chips for a total of 8. Totally confused. Who is correct please?

Also, after upgrading the OS, system started acting strange at times ( opening various unwanted apps on restart, web pages reduce in size without touching any keys, occasional freeze-ups such that option/command/esc will not work-have to turn system off/on). Will additional memory help with this.

BTW, Disk Utility First Aid indicates that all is okay.

Grateful Indeed-Paul

 

Stick with the advice from Apple, chances are your machine does not support more than 8Gb of memory. Also a module of 2Gb and one of 8Gb is not a good configuration; two matched modules of 4Gb ea would work much faster. As for your quirks after the upgrade, those are known to happen. More memory is always a good thing, but you should also check and repair the permissions on your system disk and see if that helps.

 

I think your Macbook only has two memory slots so to get 8Gb you would need two 4Gb chips.
You can get specs for every Mac ever made here: http://mactracker.ca/
If yours is the one I think it is you should go here: https://support.apple.com/en-us/HT1270

 

Both good advice from CleaverC and macuse.

What Apple says is maximum and what actual maximum are not always the same.
Get your model identifier from "About this Mac" in Apple menu, then use Mactracker to find your model and see the maximum supported.

Like CleaverX mentioned, DIMMs should be installed in equal sizes in the 2 slots to maximize performance.
I don't think that the problems you are having would be caused by mismatched DIMM sizes, but it's a possibility.
I have seen in the past with mismatched DIMMs that the order can cause problem, try swapping the DIMM slots for the 2GB and 8GB DIMM.

I would also suggest downloading one of the free memory tester and doing a thorough check of your new RAM. (always a good thing to do with new RAM)
Odd behaviour like that is symptomatic of faulty RAM or RAM not seated properly or making good contact.
You can pull out and try reseating them.