A softmod is a method of using software to modify the intended behaviour of hardware, such as video cards, sound cards, or game consoles in a way that can overcome restrictions of the firmware, or install custom firmware.
Video cards that can be modified using software to faster versions (without regard to clock speed) usually contain mostly the same hardware. Softmodding a card should not include changing the video card's BIOS, as that is a BIOS flash. Currently only four softmods are known, a Radeon 9500 NP to a 9500 Pro (128 bit) or 9700 (256 bit), a Radeon 9800SE (with 256-bit L-shaped memory layout on the PCB) to a Radeon 9800 Pro, a GeForce 6200 to a 6600, and a GeForce 6800NU to a 6800GT. The act of a softmod usually enables pixel rendering pipelines, though may also include other enhancements. A softmodded card may not always reach the same performance as the real card it has been changed to, but the difference should be very little; and generally not noticeable. The softmodding is not guaranteed to always work; sometimes the pipelines have been disabled for a reason, e.g., a defect that produces artifacts when enabled.
Softmod is also a term used to refer to modifying an Xbox without the use of a mod chip.
Softmods for Xbox used to include a font exploit installed through exploits in savegame code for MechAssault, Splinter Cell, and 007: Agent Under Fire. Usage of the Splinter Cell disc is generally recommended as any version of the game will run the exploit, whereas certain production runs of Mechassault and Agent Under Fire are needed to use the exploit. Originally, via a piece of software called "MechInstaller" created by members of the Xbox-linux team, an additional option could be added to the Xbox Dashboard for booting Linux. The Font-hack works by exploiting a buffer underflow in the Xbox font loader which is part of the dashboard. Unfortunately, since the Xbox requires the clock to be valid and the dashboard itself is where you set the clock there is problem if the RTC backup capacitor discharges. The Xbox will detect that the clock isn't set and therefore force the dashboard to be loaded which then promptly reboots due to the buffer overflow exploit. Upon restarting, the Xbox detects the clock is invalid and the process repeats. This became known as the infamous "clockloop".