Memory Issue

[SmokaSizzle70]

Hi all
Okay so when I am gaming everything is fine then I get crazy lag. I started task manager & it says I am using avg 90% of my memory. I have 8GB of Kingston HyperX Blu 1333MHZ. When I look at the processes and the value of memory being used it should be no where near 90%.
I have done a malware, virus scan and a memory test (win 8.1 pro) and I get no errors.
Is there any other tests I can do?
I wouls really appreciate some help with this.
Thanks in advance for your time.
Edit: In addition when I end the game through lag and go back to desktop task manager is showing 80% memory being used but there is nothing near that displayed in the individual amounts.

 

[barnsley]

We'll need your pc specs, what game you were playing, what Anti-virus you're running and try to replicate the problem and get a screen shot of your processes.

 

[SmokaSizzle70]

We'll need your pc specs, what game you were playing, what Anti-virus you're running and try to replicate the problem and get a screen shot of your processes.

Okay thanks for fast response
Will repost after school run.

 

[SmokaSizzle70]

Information as requested.
PC spec:
FX4100 @4.2Ghz
8GB Kingston HyperX Blu DDR3 1333MHZ
HD6850 with ATI 13.9 beta driver.
M5A78L-M USB3 with 1801 BIOS.
Xigmatek 600w PSU.
Was playing BF4.
AV is Avast free.

Thanks.