Having overclocking issues with 670

[Gamer_Pollution]

I have a Gigabyte Windforce 2x 670 and for some weird reason, when i attempt to increase the clock speed by even 20MHZ, it actaully underclocks it, from 941 MHZ to 914 MHZ according to Furmark and GPU Z. I'm kinda confused and would appreciate any help. I used MSI Afterburner and Furmark for testing, with GPU Z also. \
My specs are an i5 3570k overclocked to 4.5 GHZ, a CoolerMaster Hyper 212 Evo, an Asus P8Z77-V LE Plus, Gigabyte Windforce 2x 670, a Seagate Barracuda 3TB 7200 RPM Hard Drive, Crucial M4 128GB SSD, Patriot G2 Series 2x4 GB 1600 MHZ ram and a CoolerMaster HAF XM.
Thanks and any help is appreciated.

 

[SkyWalker1726]

that might be because of the GPU reaching a temp @ which it needs to lower the Frequency too Cool down .
i wouldn't bother ocing a 670 or 680 , the difference won't be noticeable and u would put ur VGA @ Risk ...

 

[Gamer_Pollution]

that might be because of the GPU reaching a temp @ which it needs to lower the Frequency too Cool down .
i wouldn't bother ocing a 670 or 680 , the difference won't be noticeable and u would put ur VGA @ Risk ...

At stock the CPU reaches a temperature of 60 Celsuis at 100% load. Is that temperature too high?

 

[SkyWalker1726]

if u meant GPU :

"no it's not high @ all , Gpus limit are said to be 90~100 Celcius ...
but my 680 starts lowering the Gpu frequency @ 70
it's how the kepler was designed to be , that's how it works .
and by the way mine is a windforce too "

if u meant CPU :

"if after 4~5 hours of "intelburntest" ur temps are below 85 , is would say ur fine"

 

[meatball2860]

Okay it could be your motherboard over heating so it slows and the Gpu is problably going to die so I have this issue many times with the 560 and also windows 8 will help.

 

[meatball2860]

your motherboard probably doesnt handle it.

 

[Sumukh_Bhagat]

Gigabyte?
Do you know about Voltage Lock? Gigabyte Cards are Voltage locked.

So, No Overclocking.

 

[Gamer_Pollution]

Gigabyte?
Do you know about Voltage Lock? Gigabyte Cards are Voltage locked.

So, No Overclocking.

Really? Damn, that sucks. Though overclocking a 670 is pretty pointless anyway. Thanks!

 

[Gamer_Pollution]

Best answer selected by Gamer_Pollution.