Sapphire ATI Radeon 5670 HD 1GB Temperatures

Use ATI Catalyst Control Center (or any utility) to monitor your temperature. Personally, i don't let my ATI 5770 exceed 50C and set the fan speed high when playing a game. You should be fine if you leave it at stock speeds and auto fan.

im currently using CPUID Hardware Monitor to monitor temperatures of hardwares on my system.

how can i increase the fan speed of my graphics card?

I use ATI Catalyst Control Center, it's under OverDrive tab. If you haven't overclocked and have good air flow in your case, then you should be fine in Auto, unless the room temp is high. If it is running too hot, you can try underclocking it, but that will sacrifice some of the performance.

Be warned, however, that setting your fan at high speeds constantly will decrease the life of the fan. Hopefully you will upgrade your GPU long before your fan fails. It may also be possible to get improved fans and heatsinks for your graphics card if you are really serious about it. In general you shouldn't worry too much since these cards are usually rated to run at very high temps.

Also, your computer should automatically stop if temperatures get excessively high.

ooh. my graphics card is usually at 40°-45° at idle and at 45° to 58° when im checking it in the middle of my game. is it normal at that range?

At those temps you are in good shape. I try to keep it under 50, but then I'm kinda paranoid about burning my card. I've read about graphics cards going much much higher!