Need Advice on upgrading RAM in Lenovo H420 desktop PC.

Specification Intel(R) Core(TM) i3-2100 CPU @ 3.10GHz
Package (platform ID) Socket 1155 LGA (0x1)
CPUID 6.A.7
Extended CPUID 6.2A
Core Stepping D2
Technology 32 nm
TDP Limit 65.0 Watts
Tjmax 102.0 °C
Core Speed 1596.2 MHz
Multiplier x Bus Speed 16.0 x 99.8 MHz
Stock frequency 3100 MHz
Instructions sets MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2, EM64T, VT-x, AVX
L1 Data cache 2 x 32 KBytes, 8-way set associative, 64-byte line size
L1 Instruction cache 2 x 32 KBytes, 8-way set associative, 64-byte line size
L2 cache 2 x 256 KBytes, 8-way set associative, 64-byte line size
L3 cache 3 MBytes, 12-way set associative, 64-byte line size
FID/VID Control yes

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Memory type DDR3
Module format UDIMM
Manufacturer (ID) Hyundai Electronics (AD000000000000000000)
Size 4096 MBytes
Max bandwidth PC3-10700 (667MHz)
Nominal Voltage 1.50 Volts
EPP no
XMP no
AMP no
JEDEC timings table CL-tRCD-tRP-tRAS-tRC @ frequency
JEDEC #1 6.0-6-6-17-23 @ 457 MHz
JEDEC #2 7.0-7-7-20-27 @ 533 MHz
JEDEC #3 8.0-8-8-22-30 @ 609 MHz
JEDEC #4 9.0-9-9-24-33 @ 666 MHz

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The above is my machine specs and current RAM in Slot #1 (OEM).
I'm thinking of upgrading by adding 1 x 8GB or 2 x 8GB sticks.
Will the following work in Slot #2 (Total 12GB), or should I replace both sticks (16GB)

Kingston Technology ValueRAM 8GB 1333MHz DDR3 Non-ECC CL9 DIMM Desktop Memory 8 (PC3 10600)

Kingston Technology ValueRAM 8GB 1333MHz DDR3 Non-ECC CL9 DIMM Desktop Memory 8 (PC3 10600) KVR1333D3N9/8G at Amazon.com

Thanks for any advice.

I always recommend using a kit of ram. Kits are tested to work together and individual sticks are not. Plus, when mixing brands, it is asking for trouble.

Thanks for the kind words. Sevenforums has a wealth of experienced knowledgeable members.

The Machine in your system specs and the system you listed in the post look pretty much the same. However, I would still not mix the ram. You can try it, but it can cause problems. Look up your Machine on the Lenovo web site and look at their QVL list for ram. That should be the ram they have tested to run right in that model computer.

Thanks, I hope it works well for you.