When Do You Need SLI and Crossfire?

When shopping for a video card, you should always get the single best card you can afford, unless you are planning on running at resolution that requires SLI to play games at the desired quality (which is generally 4K at high/max quality).

I started with a single GTX 760 2GB, added another GTX 760 2GB later on for SLI.

I then traded the GTX 760s for a single GTX 970 4GB.

Later on, I added another GTX 970 4GB for SLI GTX 970 4GB. This is what you see in the picture.

What Is SLI Technology?

SLI is a technology developed by the GPU manufacturer Nvidia. To get technical…Scalable Link Interface is a brand name for a multi-GPU technology developed by NVIDIA for linking two or more video cards together to produce a single output.

SLI is an algorithm of parallel processing for computer graphics, meant to increase the processing power available for graphics. Basically, SLI allows you to connect several (up to 4) matching GPUs together to act as one.

SLI setups include 2-way, 3-way, 4-way, and Quad. I’ll explain the difference between 4-way and Quad shortly.

SLI Performance Gains

SLI generally results in a 60-90% increase in framerate (though this is typically only while running a 2-way setup).

This is due to scaling, which does best in two-GPU setups (not necessarily two-card setups).

3 and 4-way

Adding more GPUs allows you to get more performance, but the gains diminish rapidly.

In addition, having more than 1 GPU will almost always require you to have a high-end CPU (at least a normal quad-core i7), and 4-way/Quad SLI will require a very high-end CPU (hex or eight-core i7, or a Xeon).

This is because when you add more GPU, you want that additional GPU to run freely, and not slow down.

This means having a powerful CPU to keep feeding the GPU information, as a lack of information will result in lag, stuttering, poor quality, and potentially crashing.

What CPU?

If you’re using a simple 2-way setup, a normal unlocked i7 will do fine (the x700K variants). Be sure you have enough power for the additional card, and proper airflow/cooling.

It’s also recommended to have proper cooling for the CPU, as there will be a substantial load on the CPU.

4-way SLI

4-Way vs Quad SLI

4-way means running 4 individual GPUs together, while Quad means running 2 dual-GPU cards together.

More cards means more work to be done, and more room for error. 4-way also adds a tremendous amount of heat, and poor scaling, as well as massive power draw.

Nvidia also does not support more than 2-way with the Pascal-series GPUs (the older cards did support 3 and 4-way/Quad). You can still run 4 Pascal GPUs, but you’ll be restricted to getting full use only in synthetic benchmarks, not games.

You also won’t be able to use the High-Bandwidth (HB) bridge that Nvidia developed specifically for the Pascal architecture.

Crossfire Technology

Crossfire is much of the same technology, and was developed by AMD.

(Almost) SLI Builds We’ve Done

Build 96 – Leftovers

Build 87 – Houdinier

Build 74 – Blenderizer

Build 70 – Firebird v2

Build 63 – Big Timer

Build 62 – Firebird v1

Build 59 – Black Falcon

Build 57 – Aries

Build 56 – The Shrenderer

Build 49 – Industrial Strength Awesome v2

Build 48 – Grimm

Build 44 – The Black Box

Build 37 – Deep Shadow

Build 19 – Storm of the Century

Build 14 – Industrial Strength Awesome

About Top Flight Computers

Top Flight Computers is based in North Carolina and designs bespoke computers, specializing in workstations, gaming computers, and water cooling.

We believe that fostering and strengthening authentic personal relationships with our customers is the most important part of our business. Above all, we want to help you get exactly what you need to be successful.

If you need more than a mass-market pre-built system, trust our technical excellence and dedication to personal service to design and build your bespoke PC.