If you're idling that's way too hot I would think. My GTX 460 when surfing runs ~10C cooler than the CPU. Also, why are the HDD's running that warm? Not really a problem but the enclosure on those things is a heat sink. Do you have both intake and exhaust fans and checked for dust lately?
Many variables, many solutions.
First of all, what third-party model of the GT240 do you run? Just to identify the cooler and heatsink aboard to aid fellow forum members.
From what I've read, the GT240 will rise by ~10C (idle) and ~25C (load) above ambient temperature. So, yeah. Your GPU is more than a little toasty.
You mentioned your computer is getting loud, that may be due to your GPU fan. The bearing and/or sleeves of the fan has worn out. Hence, the lack of sufficient cooling for your GPU. Even so, it may not necessarily be your GPU fan and can be any other fan in your PC (CPU fan, case fan).
Have you also checked the average RPM of your GPU fan? Programs like MSI Afterburner will help monitor your GPU fan's RPM in percentage. You may try manually increasing the fan speed and see if this helps lower the temperature.
Make sure to check for dust and other particles which may be blocking airflow also like DelroyMonjo said.
A couple of different solutions to various different problems:
1. Dust blockage. Clean up any dust which may block airflow. The tend to accumulate behind the fan blades. Realistically, I do not think it will reduce temperatures much. But, a simple step and maintenance that should be done.
2. Fan isn't spinning fast enough. Manually change the fan's speed and note the before and after effects.
3. Problematic/worn-out GPU fan. Swap out your GPU fan for a new one; Arctic Cooling has very cool ones. I've never heard/seen a worn-out fan for GPUs but it is not unlikely. Weirdest worn out fan I have had was my CPU cooler's.
Oh! How can I forget? If your ambient temperature is 55C, then no need to worry.
Hope it helps.