graphic card radeon 7850 1 gb seem not perform completely. Low fps and low default graphic on sc2

[seb87]

Hi all ! I just upgraded my computer with a 6 core fx amd 3.3 ghz , 2x 4 gb ram kingston , Saphhire amd radeon 7850 1 gb 256 mb graphic card and motherboard gigabyte 970a-d3.
The problem is even with all that stuff , Starcraft 2 recommended me to put my graphic settings to medium or low .Even setting that sc2 say it depend VRAM, recommended me medium as if i get only 256 mb when i have 1024 ,mean suppose setting being to ultra. And if I put it to ultra , starcraft tell me that my computer slow the game and i should put my graphics lower . I tested the fps rate , and at menu i get 60 , and when in game ,it start dropping and i finish the game with less than 20 fps . As if more units are on the map , lower is the fps . I can't believe with that computer , i can't easily play starcraft 2 with high settings ! Is there something that block my graphic card to perform normally or anything else ?
When i did a test with Furmark i got, with no preset ; 32 fps , with 720; 52 and with 1080 ; 29 !
My cpu and memory are never get more than 50 % of utilization. No virus , and all drivers updated . I just don't understand . thank for your help !
( sorry for my english ) ^^

 

[swifty_morgan]

run the game at 1200 resolution. what happens?

 

[seb87]

I put the resolution to 1280x720 .It was really better , fps at 60 at start and stay like that for the first part of the game ( 4 vs4 ) but the image quality was really lower and the image doesn't fit with the screen ( black borders ) and i finished the game at 20 fps. I bought a full hd monitor and i plugged it in hdmi ! I don't know if it change something . I hope not , the difference between 720 and 1080 is big ! and it didn't change recommended settings of sc2. I think my graphic card should support full hd easy , no ?