Socket 5 / 7 / Super-7 Motherboards
Socket 5 was the successor to Socket 4. Socket 5 used 3.3V for the processor instead of the 5V that Socket 4 used, resulting in a much lower power dissipation. This is good, as this will decrease the amount of heat (remember that AT cases had very poor ventilation) that the CPU will produce. Socket 5 used 32-bit FPM or EDO memory modules and they usually had to be installed in pairs. Supported FSB's were usually 50MHz, 55MHz, 60MHz and 66MHz. Usually Socket 5 supports Pentium CPU's of 75MHz to around 133MHz, Winchip (though not all Socket 5 boards will be compatible with Winchip CPU's) and Pentium Overdrive. This makes them somewhat more flexible then Socket 4, but not as flexible as Socket 7 or Super 7 and as Socket 7 and Super 7 are much more common, Socket 5 is a lesser option when looking at flexibility from a CPU perspective. Though Pentium MMX CPU's are not officially supported (as they run on a slightly lower 2.9V), Pentium MMX CPU's may run just fine at 3.3V.
No Socket 5 ATX boards are known to exist. No Socket 5 boards with AGP are known to exist. Usually Socket 5 boards had PCI and ISA slots, though 1 or 2 VLB Socket 5 motherboards may have been made.
Socket 5 was very short lived and was quickly replaced by the much more well known Socket 7
Socket 7 was originally created by Intel as a successor to Socket 5, though many different manufacturers have created compatible CPU's for Socket 7. Socket 7 was the first CPU socket to support a split rail for it's CPU's. Also Socket 7 motherboards featured a higher maximum CPU speed compared to Socket 5. Even though Socket 7 usually ran from 75MHz to 233MHz,some motherboard manufacturers created motherboards that were able to run chips at speeds of up to 400MHz (and higher when overclocking the FSB). Socket 7 chip sets were again designed for FPM or EDO RAM, though some of the later ones were designed for SDRAM, such as Intel 430VX, Intel 430TX, VIA VP3 (though the earliest known Socket 7 boards with support for SDRAM only supported memory modules to a maximum of 32MB when the memory module is dual sided. Running a higher density module will usually result in half or three quarters of the memory not being seen by the motherboard). Usually EDO and FPM could be mixed (as long as the EDO and the FPM modules are installed in pairs), but EDO and FPM could not be mixed with SDRAM usually, as they have different operating voltage.
Socket 7 also supported a small variety of FSB's, ranging from 50MHz all the way to 83MHz, though what FSB's are supported depends on the motherboard itself. Usually Socket 7 motherboards had 4 settings for setting the FSB. 66MHz was the highest officially supported FSB by the vast majority of Socket 7 motherboards, though later motherboard manufacturers often officially supported higher FSB's like 75MHz and 83MHz (even though quite often this did in fact overclock the chipset).
A large variety of CPU's is supported by Socket 7, ranging from Intel to AMD, Rise, Winchip and Cyrix. Only Super 7 provided even more flexibility.
Most of the time Socket 7 boards are AT form factor (or propriety). Sometimes they come in ATX form factor. The vast majority sport PCI and ISA slots (only a few had AGP).
Super Socket 7
Super Socket 7 (or Super 7 for short) is basically the same as Socket 7, except in that it officially supports a 100MHz FSB. As Intel left Socket 7 for it's Slot 1 solution, Intel's competitors were left with an aging platform.
As Super 7 had no official support from Intel, no Super 7 Intel CPU's nor chipsets were made, this was left to it's competition. Overall, Super 7 provides great flexibility in CPU speed, ranging from around 100MHz to almost 600MHz (and higher when overclocking). Super 7 was also the last socket to make extensive use of jumpers for setting up the CPU multiplier, FSB and CPU voltage. Super 7 does often have AGP issues (be it either by software (because of instable drivers) or because of hardware (due to the AGP slot not being able to provide enough power to it's AGP graphics card)). This can be worked around by making use of a PCI graphics card. Also the software issues can be worked around by using an AGP 3DFX graphics card, as 3DFX graphics cards made less use of the features that AGP provided, it was thus also less prone to cause any issues.
Usually Super 7 comes in ATX formfactor, though AT Super 7 boards do exist. Usually they have an AGP 2x slot (no Super 7 motherboards with AGP 4x slot were ever made). Even though Super 7 shares the same general dimentions with Socket 7 and Socket 5 on the lower spectrum and Socket 370 and Socket A on the higher spectrum, the fitting of a Socket 370 or Socket A CPU cooler will often not work as there are often motherboard components in the way of the larger CPU cooler, preventing it's installation.