Consider the facts below to help you determine the Rackmount Chassis that’s right for your project

Your Rackmount Dimensions

All standard rackmount chassis come in a width of 19-inchs. Rightfully, this is an industry standard width that today's rackmount computing systems abide by. However, the height dimension, or the number of vertical spaces it occupies in the rack itself, dictates the chassis’ scalability to your application.

Units come in “U”s, with each “U” equaling 1.75 inches of vertical space in a rack system. Advantech offers solutions from 1U to 7U rackmount systems.

Will You Require 1U, 4U or 7U?

Naturally, your application will determine how many units your industrial rackmount solution requires. Here are some examples:

• Requirements for a system with two to a maximum of four full-sized PCI or PCIe slots can usually be met with a motherboard system in a 2U chassis.


• If you have requirements such as a dual backplane chassis with two full-sized single board computer boards and peripheral cards, they plug in perpendicular to your backplane, requiring more vertical space. Therefore, you require least a 4U rackmount chassis to accommodate needs for multiple cards. (See our Backplane Selection Guide for more information on choosing backplane architecture.)


• If you are in need of a rackmount system utilizing RAID 5 or RAID 10 - requiring at least three hard drives - then you need at least a 2U chassis in order to house them.


• If you plan on your chassis housing a motherboard computer design and less than four peripheral cards, a riser card can enable a “butterfly” backplane arrangement accommodating three cards. This way, you can often keep the form factor down to the 1U size.

Another good rule-of-thumb is that if you plan on using PCI peripheral board slot space in your motherboard, it is best to shop for a 2U system or more. In a system with backplane architecture featuring more expansion, the answer is usually found in a 4U system. If you would like to talk to a sales engineer about your exact requirement, contact one here.

Slot selections

Card size and the type of bus/expansion (ISA, PCI, PCIe) are the most frequent factors in determining slot selection requirements for your rackmount solution. It is common that single backplanes featuring several slots -- 7 to 14 slots, for example -- take significant space going depthwise. Thus, if you require a rackmount solution containing nine full-sized peripheral boards, you will need a 20-slot rackmount chassis to accommodate them.

When a rackmount solution requires a PICMG 1.3 backplane with a combination of PCI and PCIe slots (especially 9 to 14 slots), rackmount chassis extend deeper to provide room for the extra slots. Therefore, your rack depth space requirements must be taken into consideration.

Depth of a 20-slot rackmount chassis

Single or Redundant Power Supply?

Power supply is a factor in your rackmount solution that should not be overlooked when ordering. Many higher-end mission critical servers and network equipment incorporate a Redundant Power Supply (RPS), so that if the main power supply were to fail, the rack would have a backup or fail-safe to fall back on, so as to eliminate downtime. A common data center design uses a minimum of two sets of independent circuits within each rack.

Ideally, both sets of circuits should come from different power sources capable of independently handling the entire anticipated load capacity of the rack. If it sounds like it’s time for you to consider your application “mission critical”, then you should include a redundant power supply in your configuration.

Heat Dissipation

Let’s face it, things are going to start getting a little warm as you add computing power into your rackmount solution, and heat is the enemy of electronics. Some considerations to take into account:

• Due to the greater volume inside the casing walls, chassis greater than 1U dissipate heat well.


• A design that requires more than four CPUs will often require a casing with added flow, or more than one chassis fan, so plan your unit requirements to accommodate this.


• A rackmount application requiring 24/7 or similar runtime usage may require more than one chassis fan for extra heat dissipation.


• If your rackmount chassis contains multiple CPUs and you are concerned with overheating, positioning the rackmount system where the spaces above it and below it are unoccupied may provide the required heat dissipation.

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