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 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 custom built computers, focusing on bespoke desktop workstations, rack workstations, rack servers, and gaming PCs.
We focus on the Raleigh/Cary/Apex/Durham area, offer free delivery within 20 miles of our shop in Cary NC, can deliver within 3 hours of our shop, and ship nationwide.
We work with local NC partners for other tech services, such as computer repair and managed IT. Call us at 919-500-5002 or email us at sales@topflightpc.com to inquire about a build!
Check out our past builds and live streams on our YouTube channel!