NVIDIA RTX 4090 Power Requirements & Compatibility Guide

PowerSpec_MichaelB · October 2022

It's no secret that NVIDIA's RTX 4090 is a powerful card. So powerful in fact, power delivery and cooling has become a real challenge with this generation. To overcome this, the new 12VHPWR connector is used to allow up to 600W of power delivery in addition to designing new cooling solutions to handle the 450W of heat these cards can generate at stock clock speeds. That's right... 450W of heat before overclocking is even factored in.

With the higher power requirements and thermal envelope in mind, it is important that we pick the right chassis and power supply to pair with these cards. In terms of power, NVIDIA recommends a minimum PSU capacity of 850W. As for our testing here at Micro Center, we would recommend a minimum of 1000W. There are a few reasons as to why we would recommend a higher capacity:

Additional power headroom for overclocking CPU & GPU
Additional power to factor in capacitor aging over time
Higher capacity power supplies allow for better power efficiency curves under load
Improved capacity for future component upgrades

We would also recommend buying power supplies with the new CEM5 ATX 3.0 standard as they include the previously mentioned 12VHPWR connector without the need for adapter cables. Now, you can certainly use the power adapters that come with your RTX 4090 graphics card, they are safe and rated for the higher current these cards require, but a native 12VHPWR connector looks cleaner and would be easier to cable manage due to the reduced bulk.

As for chassis compatibility, this is where things get very tricky. With this new 12VHPWR connector comes a few caveats in terms of how we route and manage our cables. The previous 8-pin connectors (mini-fit jr) could be bent pretty aggressively without much cause for concern. Reporting online shows that the new 12VHPWR connector does not share the same flexibility and must avoid aggressive bending near the connector or there may be a risk of component damage from burning cables or connectors. Here are a few examples we found online:

(Images courtesy of Cultists Network)

Based on the information we found online, this damage can occur if the wires leading to the 12VHPWR connector are pulled too tightly causing the plug to bend inside of the connector. This can cause a reduction in the contact area on the wire which can change the electrical resistance in other pins, leading to burning/melted cables. To avoid this, it is recommended to allow for at least 1.25" (31.75mm) of clearance from the 12VHPWR connector before bending the cables. See the following examples for the proper and improper way to do this:

Proper Method:

Improper Method:

Now that we've explained the safe bend radius of the new 12VHPWR cables, we can factor that into chassis compatibility. The easiest way to determine if your chassis will be compatible with your RTX 4090 card is to take the width of your RTX 4090 and adding 1.25 inches to that value. From there, check your chassis specification page for the Max CPU Cooler Height specification. I know it sounds weird using the Max CPU height to determine GPU support, but that is going to be the easiest metric to gauge compatibility for now as cases currently do not have a "Max GPU Width" specification. Take your combined GPU Width+1.25" and see if it fits within that Max CPU Cooler Height specification. If the answer is yes, then your card is compatible. If the answer is no, we would recommend buying a chassis with a wider internal depth to support the new GPU. Let's do an example to determine if an MSI RTX 4090 Gaming X Trio will fit in a couple of different cases.

Example 1: Lian Li O11 Dynamic EVO Tempered Glass ATX Mid-Tower

Max CPU Cooler Height: 167mm (6.57")
MSI RTX 4090 Gaming X Trio Width: 140mm (5.51")
Card Width + Cable Bend Radius (1.25") = 6.76"
Chassis NOT recommended with this particular RTX 4090

Example 2: Lian Li Lancool II MESH Type C RGB Tempered Glass ATX Mid-Tower

Max CPU Cooler Height: 176mm (6.93")
MSI RTX 4090 Gaming X Trio Width: 140mm (5.51")
Card Width + Cable Bend Radius (1.25") = 6.76"
Chassis is compatible with this particular RTX 4090

Lastly, let's talk transport. Whether you are heading out to a LAN party at a friend's house, or buying your RTX 4090 powered desktop from your local Micro Center store, you'll want to exercise caution when transporting a system with a heavy GPU. Looking at most RTX 4090 models online, these things weigh in at nearly 5lbs and some models are even heavier. That is a lot of stress to put on the narrow PCIe connector, which is why we recommend utilizing proper system orientation when transporting your system. The best method is to keep the GPU vertical if possible, especially with the weight oriented towards the rear of the PCIe bracket where the card is screwed into the chassis. This will keep that excess weight off the PCIe slot and help maintain the heavy card in an upright position. All PowerSpec systems are boxed in this orientation by default, but custom builders will want to ensure they keep their original chassis boxes and orient their systems in this same vertical position to avoid damaging their graphics card and other internal components. After all, if that 5lb behemoth breaks loose inside your chassis, it is likely taking other components with it.

Here is a quick orientation guide to help demonstrate the desired vertical position of the GPU:

Correct Orientation:

Incorrect Orientation:

We hope this helps with finding the right PSU and chassis for your RTX 4090. When in doubt, check with the sales experts at your local Micro Center store. Not only can they assist with ensuring your parts are compatible, they can also provide advice on how to get your components home safely and ensure you are ready to enjoy the insane levels of performance that these cards have to offer. If we missed anything or if you have any questions, feel free to comment below!