GTX 570 fighting with mindcrack

[Zsombiee]

Hi, first of all I'm gonna show my computer setup:

My issues are the following:
When I'm using Sphax PureBDcraft 128x128 texture pack, (I think my setup with better configuration must handle this)
my gpu memory usage increases to maximum , in my opinion that couses the FPS deacrease ingame.
Is there any solution to fix this?
I tried the 64 bit texture pack too it uses arund 80% of my GPU memory .
Any ideas?
btw I am using optifine and my computer tries to handle the memory loss --- my cpu runing 50% constantly, and using arund 1,5-3 GB ram

If u need more information I can screen informations ingame, I can show you the current usage of the things like gpu memory etc.

 

[Scaffolding]

Have you already asked for help with this problem in the Sphax FTB thread?

I'm using an ATI card (6850 w/DDR5 1024 MB) and GPU load is never over 23% but memory usage averages 70-90% with 128x128. Unless I did something wrong also then this is probably intended, I mean 128x128 per block in minecraft is kind of a lot.