Problem after clean install

[Kyriakos Kypraios]

Here I am once again for asking for a piece of advice... Here's the thing...
I got a new GPU,Gigabyte R9 280, and after the instalation I peformed format on my HDD and did a clean install at Windows 7 Ultimate x64. The pc before was running smoothly and didn't have any problems. After the clean install and the drivers install, pc felt like "heavy" and laggy, also while I was watching videos on youtube I got a black screen saying Ati Catalyst failed anf Smart6 while I was trying to use smartboost to get my CPU at 3.0 GHz got me an error saying it didn't recognise my CPU, while before it didn't have any problem at all . Also had a hard time installing windows updates and had to use commands in order to go through this. In the only game I've tried so far (Metro Light ) pc behaves quite well without having lags or something like that.
My current specs are
i5-750 stock
Gigabyte P55-UD3 Rev 1.0
Corsair 650Watt PSU
8GB ram 1066
Gigabyte R9 280

The difference before and now is the GPU (Before I had the HD 5850).
I'm at the need of your help if anyone got any suggestion because because I'm getting a litrle cazy.

 

[smorizio]

did you install the intel or amd chipset drivers if not the mb pci slot not going to work right. also check with the mb vendor see if there any new bios updates. with newer gpu sometime there bios bugs that crop up.

 

[Kyriakos Kypraios]

I've updated bios and intel but now feels more unstable . Anyone got anything to propose?
And also after updating BIOS and installing Gigabyte Smart6. My GPU drivers stopped working and had to reinstall, i got it recognise my CPU but i got a message tha my Standby Modes (S3/S4) are not supported. 🙁

 

[Kyriakos Kypraios]

Update: Wierdly and out of the blue after I updated the BIOS, downloaded newest drives on both intel chipset and my GPU, I tried the Smart6 Easyboost and set my CPU's clock at 3.2 GHz (i5-750 2,6GHz stock), kind of like OC... The pc after that feels more stable and the Standby Issues were fixed. Is that possible that after the CPU's OC that the whole system got stable? I mean... I've ran all possible stress tests for both the CPU and the GPU after the OC and the pc was stable, temperatures on full load 53°C for all cores of the CPU and 58°C for the GPU. Is that even possible or is it going to blow up? 😛