Hardware Reference
In-Depth Information
to provide the extra power that would be missing if you connected a 20-pin main power
connector from your power supply. The documentation for these motherboards refers to
thisasan
alternate
or
auxiliary power connector
.Someboardsincludedbothstandardand
SATA style drive connectors to supply this extra power.
If you plug a 24-pin main power connector into the 24-pin socket on the motherboard,
thealternate orauxiliary powerconnection isprobablyunnecessary.However,ifyouplug
a 20-pin main power connector into the 24-pin main power socket on the motherboard,
andthatboardhasoneofthesealternate orauxiliarypowerconnectorsonboard,thenyou
should probably use it. In that case simply select a spare peripheral (disk drive) power
connector from the power supply and plug it into the alternate or auxiliary power con-
nector. Most power supplies have several extra peripheral or SATA power connectors for
supporting additional drives. Using a 20-pin main and the alternate or auxiliary power
connector satisfies the power requirements for the motherboard and any PCI Express x16
video cards drawing up to 75 watts.
Asasidenote,youshouldbecarefulwhenplugginginthemismatched connectorssothat
they are offset properly. The main, +12V, and PCI Express graphics connectors are Molex
Mini-Fit Jr.-type connectors that are keyed by virtue of a series of differently shaped
plastic protrusions used around the terminals, which fit similarly shaped holes in the mat-
ing connectors. This keying is designed to prevent backward or improper off-center in-
sertion, but I have found two problems with the keying that should be noted. One is that
some alternate low-quality connector brands are built to looser tolerances than the origin-
al high-quality Molex versions, and the sloppier fit of the low-quality versions sometimes
allows improper insertion. The other problem is that, with sufficient force, the keying on
even the high-quality versions can be overcome. Because plugging a 20-pin connector in-
to a 24-pin socket—or a 24-pin connector into a 20-pin socket—is designed to work even
though they don't fully match up, you need to make sure you have the offsets correct or
you risk damaging the board when you power it up.
Dell Proprietary (Nonstandard) ATX Design
Most of these systems are no longer in use, but if you upgrade or repair any Dell desktop
systemsmadebetween1996and2000,youshouldbeawarethattheyusedanon-standard
design, and upgrading either the motherboard or power supply can result in the destruc-
tion of the motherboard, power supply, or both!
When Dell converted to the ATX motherboard form factor in mid-1996, it unfortunately
defected from the newly released standard and began using specially modified Intel-sup-
plied ATX motherboards with custom-wired power connectors. Inevitably, it also had
