Hi All,
I use MSI Afterburner for some readouts and HWINFO32 to provide other readouts that AB doesn't have. HWINFO32 is also compatible w\ Riva Tuner Statistics Server (the overlay software companion w\ MSI AB that I also use....both authored\written by Unwinder) so readouts from both AB & HWINFO32 can co-exist on the same RTSS overlay (RTSS has been known to work seamlessly w\ Dx11 and Dx9 API's in most cases).
Using all 3 pieces of software running in the background the combined usage is .6% CPU core usage, 12.8Mb mem usage as measured on my box thru TM.
The largest user is HWINFO32 which has a CPU priority setting of "Normal" and is the 1 that is showing all the CPU usage and approx. 70% of the mem usage on my system......which isn't bad at all but is par for the course due to it's CPU priority level ranking.
Both MSI Afterburner and RTSS have a CPU priority setting of "Below Normal" which is what you want w\ a good, well written monitoring software that isn't taking up unnecessary CPU cycles to operate.....both of these show 0% CPU cycle usage (means that these softwares do not need any continuous CPU core processing time to actually run so they co-exist very well w\ other running processes.....AB uses 1.4Mb of mem and RTSS uses 3.2Mb of mem when running so these 2 are very good monitoring softwares to use for continuous CPU\GPU monitoring purposes IMHO.
Hope this helps.