Low resolution and graphics problems in Dell Studio 1558

[EiDay]

Hello,
I have problem with graphics, my current resolution is 1024x768(1366x768 native) and everything work so slow.
Two years ago I installed yosemite on this same laptop and I had the same problem, after some time I fixed it. But I don't remember how. Propably with a bootflag.

Specs:
Model: Dell Studio 1558
GPU: ATI Mobility Radeon HD 5470
CPU: i5-450M (2.4 GHz, 3 MB cache)

 

[RehabMan]

Hello,
I have problem with graphics, my current resolution is 1024x768(1366x768 native) and everything work so slow.
Two years ago I installed yosemite on this same laptop and I had the same problem, after some time I fixed it. But I don't remember how. Propably with a bootflag.

Specs:
Model: Dell Studio 1558
GPU: ATI Mobility Radeon HD 5470
CPU: i5-450M (2.4 GHz, 3 MB cache)

AMD Radeon/ATI graphics card info:

http://www.insanelymac.com/forum/forum/174-ati/
https://www.tonymacx86.com/threads/radeon-compatibility-guide-ati-amd-graphics-cards.171291/