Which Slot Does My Ram Go In

Posted on 3/26/202222.08.2017by admin

When purchasing a new Server, Workstation or PC to support an expansion card one of the most important things to determine is what type of slot does the motherboard have. There are 3 types of slots that have been used for over the years: ISA, PCI, and PCI Express (PCIe). These are also the most common types of slots that computer motherboards have had for expansion cards. Let’s take a look at each of these:

First slot of second channel (B1) Second slot of first channel (A2) Second slot of second channel (B2) And so on. If you need to install multiply modules it is best to add them one by one. Installing memory is not hard, but my advice is to have motherboard manual open and ready. Those slots rarely come in any kind of sane order. Just built a PC and unsure whether or not it makes a difference if I use 2 adjacent slots or 2 alternating slots. MB: Asus m5a97 evo r2 RAM: Corsair vengeance 1600mhz DDR3 8gb (x2) If I use adjacent slots (not colour coded) then will it run slower or will windows read each stick separately.

ISA Slots

The ISA Slots are shown in Green in image to the right. This is the oldest slot type that is still available today. Computers with ISA slots are no longer available from major computer manufacturers, Ram PC Systems still sells industrial class systems with ISA slots.

PCI Slots

PCI slots were the replacment for ISA slots. The PCI Slots are shown in the Red box in the image. PCI slots come in several different versions including 5 volt and 3.3 volt slots, and 32-bit and 64-bit PCI-X slots. PCI slots are going away as well but are still available from some major computer manufacturers but they usually only offer one PCI slot. Ram PC Systems has several different systems available with 2 or more PCI slots.

PCI Express Slots

PCI Express slots are the replacement for PCI slots, and also AGP (used only for video cards). PCI Express, also labeled as PCIe come in numerous bus widths labeled: x1, x2, x4, x8, and x16.

Choose memory

There are two main factors in memory: type and speed.

By type most of it is one of DDR, DDR2 or DDR3 (unless you are looking at really old computer). Memory of different types is not compatible mechanically or electronically. Motherboards usually have slots for one specific kind of memory, some rare models can support memory of two types (but not at the same time).

Speed of memory is faster for newer types, but also differs in margins of every type. Motherboards might only support slower speed than memory can come with. Memory of different speeds will in general work with any motherboard of required type. Slow memory will work at its speed even if motherboard can go faster. Fast memory will slow down to match motherboard if needed.

So you need memory that matches motherboard in type and (best case) speed. If adding memory it is also good idea that new modules match old ones in parameters and brand.

Manufacturers always provide (in manual and online) information on what memory motherboard supports and larger brands even offer lists of practically tested modules for each motherboard.

Choose slots

I remember times when you just had to stick modules in, but those are gone.

Currently most of motherboards/processor combos support at least two memory channels. I think there are already rare (for now) configurations with three channels.

Different channels correspond to different physical slots on board. The idea is that memory must be balanced between channels and that requires them to be filled in specific order.

Motherboard manual has diagram of slot channels and numbers. For example like this one:

Letter commonly refer to channel, numbers commonly refer to order inside channel. In usual case (when manual doesn’t have other explicit instructions) slots must be filled in following order:

First slot of first channel (A1 in example)
First slot of second channel (B1)
Second slot of first channel (A2)
Second slot of second channel (B2)
And so on.