Before you do anything look through toms hardware site for reviews and overclocking possibilities for the 7300 as it might not be worth the risk of hardware failure. And also check your warranty as it might not cover overclocking and if something does go wrong.....well your screwed Also the site has helpfull articles on overclocking, like manual overclocking via the bios (so long as you have the right motherboard and bios version). Overclocking the PCIE slot can increase performance by up to 35% alone depending on the card with minimal stress on the card. Some Windows overclocking utilities are not reliable enough as they do not do enough torture testing to guaranty stability or health of the harware. One you could look at if bios adjusting is not your thing is Ntune from the Nvidia site, its not bad but still is not the best way to go for performance increasing vs reliability/stability of the system. Bois overclocking is definately the best way to go for performance increase but its not for everyone of course. You could try both together which could provide some impresive results but just be careful, do things very small increments and test, if stable increase more and test again and so on (Look at the guides for step by step instructions, don't get impassiant). There is my advise, take it or leave it, your choice.
Nvidia Ntune works in the same way and you can do it automatically with a 3 hour fine tuning session that will make the changes in small increments and tests them repeatedly and adjusts accordingly. If the systems hangs or crashes it automatically restarts and continues (dropping back the the adjustments and retests then increases again) but it is only benificial with the right hardware as some do not overclock very well. Also if you overclock too much you may higher clock and memory speeds with full stability but will actually see lower performance then a lower overclock setting depending on the task. Example is my old system, I ran Ntune and got an overall system improvement of 30% but with no increase in performance during gaming and if the overclocking software you use creates profiles to be loaded at startup of the OS or particular games you can't be sure it loaded the profile properly or even at all as this what I think was the case with mine and this can also cause problems with your GPU causing lower score/FPS. And system or just GPU strain needs to be looked at as it can cause increased wear. And yes you should look at cooling as this can play a large part and I do not recommend disabling the temp monitor as you don't know if temps are getting to high but if any part of the system gets to hot to touch for any longer than a second or 2 then stop. If you hit stability problems it may be hitting the limit of something else like transfer speed through the PCIE slot so that will need adjusting, memory timing might be a problem. Overclocking takes a lot of passiance and troubleshooting to get it right.