Single stick, so it may be easy to pair with the existing one in a pre-built PC. A couple of bad reviews on Newegg but only 5-star ones on Amazon.
Kingston ValueRAM 8GB (1 x 8GB) DDR4 2666MHz DRAM (Desktop Memory) CL19 1.2V DIMM (288-pin) KVR26N19S8/8
- $24.99 – $5 off Promo Code EMCUVUU29 = $19.99 + Free Shipping