Monday, August 15, 2011

A Visual Guide to PC Components Pt. 1: CPUs and Motherboards

Though the thread tends to attract those who are already computer-savvy enough to know what the inside of a PC looks like, not everyone who can competently wield a computer knows what individual components go into building one.  The following is a visual guide to some salient PC components, for the edification of potential PC builders.  The important thing isn't the specific model of the parts you'll see below, but the general understanding of what individual components look like and where they go in the system.  Apologies in advance for any cruddy photos, I'm no photographer and I'm working with a relatively ancient point-and-shoot.


AMD Processor (Athlon II X2 250)

AMD Processors generally have an entirely flat heat-spreader that covers most of the silicon wafer.  You can see the designation of the processor there on top (AMD Athlon II) along with the model number.  You can't see this, but on the opposite side of the CPU are the pins, which slot into the socket on the motherboard, where they touch the contacts inside the socket.

Intel Processor (Intel Core2Duo E4500)

Though this is an older model CPU from Intel, they've been using roughly the same wafer size and heat-spreader design for at least the past 3 processor generations, and it seems unlikely to change any time soon.  Once again, the model number and CPU type are shown on top.  Unlike the AMD CPU, the heat-spreader has a couple "steps".  Modern Intel CPUs reverse the traditional CPU/Motherboard interaction: the contacts are on the CPU, while the pins are built into the motherboard socket.


AMD Micro-ATX Motherboard (ASRock 880G LE AM3)

The above is an AMD AM3 Socket motherboard (which will eventually hold the AMD Athlon II X2 processor you saw earlier).  The motherboard is based on the Micro-ATX form factor, so it's smaller than a standard motherboard, and comes with a maximum of 4 expansion card slots.  I've indicated some points of interest on the motherboard for you to take a look at.

  1. 4-Pin CPU Power:  Power from the PSU cable that plugs in here is directed to the CPU.  Higher end motherboards will have 8-Pin power connectors, in order to provide more power to the CPU, which assists in overclocking, or in running higher powered CPUs.
  2. VRM system:  Here you can see the chokes and MOSFETs that make up the VRM system (the system that takes 12V power and converts it to lower voltages) for the CPU.  If you count the chokes, there are 4, pointing to 3+1 power phases, which isn't great, but it's for a media server, so I don't need much.
  3. CPU Socket:  This is the socket for an AM3 CPU.  The socket arm swings up, you orient the CPU correctly, and all the pins drop into the little holes in the socket, then you swing the arm back down.  The plastic bracket around it is for CPU coolers.
  4. DIMM Slots:  This is where your RAM goes.  You pop open the little arms on the sides, then seat the RAM.  You'll know it's fully in when the arms click in and secure it on the sides.
  5. 24-Pin Motherboard Power:  Like the CPU Power plug, you'll run a cable from your PSU to this.  In older PCs (and some modern low power systems) the only thing necessary to run the system was this connector, which also delivers some power to the CPU.  Aside from that it delivers power to the rest of the motherboard components, and any expansion cards that are power strictly by the slot they're placed in.
  6. SATA Ports:  Here we have 3 SATA II data ports.  Drives (Optical Drives, Hard drives, Solid State Drives) are attached to these ports via a SATA cable.  Depending on the motherboard, you might see ports oriented as the are here, perpendicular to the PCB (Printed Circuit Board) or oriented parallel to the PCB.
  7. PCI-E x1 Slot:  This is a PCI Express x1 slot.  The x1 indicates available bandwidth on the slot.  x1 slots are used for basic expansion cards, like Network Interface Cards (wired or wireless) and sound cards.
  8. PCI-E x16 Slot:  PCI Express x16 slots are physically larger than lower bandwidth slots and are mostly used for the addition of discrete graphics cards.  They are compatible with any lower-requirement expansion card (you can use a x16 slot to run an expansion card that needs a x1 slot).
  9. PCI Slot:  PCI slots are probably the oldest design still incorporated into modern motherboards.  Regular PCI is slower than the PCI-Express interface and is largely useful for legacy expansion cards that you aren't willing to part with (like if you have a really old modem or NIC that you'd like to keep using).
Intel ATX Motherboard (ASUS P8P67 Pro)

So here we have an Intel motherboard based on the ATX standard.  Full ATX motherboards have a maximum of 7 expansion card slots.  Otherwise the functions on this board are largely identical to the AMD board above.  This board does have double the available DIMM slots for RAM, 2 more SATA ports with all the SATA ports oriented parallel to the PCB, and 8-Pin instead of 4-Pin CPU power.  The VRM system is also located under passive heatsinks around the CPU socket.  You'll also note the cover over the CPU socket.  Because the CPU socket for Intel motherboards contains pins, rather than contacts, a cover is necessary to protect them while not in use.

And with that, we come to the end of our regularly scheduled programming.  We've familiarized ourselves with CPU and Motherboard design, expect to see a visual guide to the PSU soon.

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