Android Revolution HD developer mike1986 came across a bug in the stock software released with the HTC One X. The Tegra 3 power management and scaling software didn't seem to function properly, and he looked deeper into it.
According to mike1986, an application identified as ‘NvCPLSvc.apk' was misplaced by the HTC developers. Instead of residing in the /system/bin/ folder (as it is now), it is supposed to be in /system/app/.
Along with the custom ROM, Android Revolution HD, the developer was good enough to release a separate fix package. You can find it here on the XDA Developer Forums. To apply this patch, HTC One X users must plug their phones into a computer and ‘push' the fix to the phone using the ADB development application. Then, the file permissions for the APK need to be modified so the phone can use it without issues. To do all of this, your phone must have USB Debugging enabled, and though it's not made clear in the XDA thread, it's likely that your device will need to be rooted.
It's expected that HTC will release an official Over The Air update to fix this problem, along with any others that turn up during the One X's initial ‘run in' period. If you're keen to repair this problem yourself though, it's not a difficult procedure. People who have completed this process report a battery life increase of 10 to 20%. Whether that is worth it or not, you decide.