Question RAM upgrade performance issues

[Wardfred]

Upgraded RAM from 8 to 16GB. With 8GB, on a particular game, I got medium FPS with very low latency but very large low FPS spikes. With the new RAM, the spikes have gone but I only get 20 FPS on average now, with a very high latency of 100+ ms. The RAM sticks are the same make as the old ones and are running at well over 2500 Hz. How can I fix this ?

 

[rgd1101]

full system spec? include make and model of the psu

 

[Wardfred]

full system spec? include make and model of the psu

processor - Intel(R)Core(TM i5-6400 CPU @2.70GHz
Installed RAM - 16GB
GPU - NVIDIA GeForce GTX 950 (but a 1660 super is coming in a few days)
MotherBoard - Gigabyte B150M-DS3H-CF
PSU - aerocool ACP-1500HG

 

[rgd1101]

Installed RAM - 16GB

exact model?

 

[Wardfred]

Crucial ballistix gaming memory, 16GB kit, ddr4-3000, 1.35V