Lag with playing games : Sapphire Radeon HD 7850 2gb oc

JwvdM

Honorable
Aug 18, 2013
21
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10,510
I bought a new computer a couple of months ago and i'm not realy a gamer anymore but at the moment i have some free time and i wanted to play assassins creed 4.

Google says the recommanded system req are:
CPU : Core i5-2400S 2.5GHz or Phenom II X4 940
GPU : GeForce GTX 470 or Radeon HD 5850 1024MB
RAM : 4GB

I have:
CPU : AMD FX-6300
GPU : Sapphire Radeon HD 7850 2GB OC
RAM : 8GB

But still when i try to play the game the game is still very laggy ( and i almost know for sure it's the GPU), and i dont know why.
When i look on youtube there are people playing the game without trouble with the same GPU.

I recently re-installed windows 8.1 and made sure everything was up to date.
But also that made no diffrence

I also try to overclock my CPU and GPU with Catalyst Control Center.
But also that didn't work, i did the following :
CPU : 3.5Mhz to 4.0Mhz
GPU : core clock 920Mhz to 1010Mhz ( dont know for sure if i can go higher but max is 1050 on the program. ) and the memory clock 1250 and it stay 1250. ( max on the progam is 1450. )
I had the idea it didn't even help a little.

I also had the same problem with a game called Metro Last Light and sometimes it showed some realy strange looking graphics.

I don't realy know what to do anymore.
I hope one of you can help me.

Also i have one big screen (101cm) and a small screen (38cm) on the side?
I haven't try it out without the small or big screen, but i think that isn't the problem.