My comp has chams?

Ok, to start this off, i play this game with a nice fps of 60-90 at my moms, its a very nice fps and im fine with it. But when i go to my dads and use my laptop there, i can see through thin walls. No i dont have chams, or any of that, its this computer. I have a hp pavilion zv5000, if you google it, you'll find out its a terrible computer.

I had to do some hefty tweaking to be able to partially play this game. I cant do 10+ ppl in a room or my fps will go to a 15-25.

So i did everything i could to lower the graphics, and in-game its all choppy, some of the textures fade away, and thats why i can see through them. Heres some examples:

As you can see, i can look through the SAS helmet, and thats his face right there



In this one, i can see through the Anacondas cylinder thing, and i can look at the bullets


This last one, i can see through this lil' piece of concrete


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I dont have hacks at all, its my computer, i would just like to know why this is so?