The Nikon D500 Dual-Slot Bottleneck, and How to Avoid It

The Nikon D500 has a well-earned reputation as an APS-C DSLR built for speed, making it a big favorite among wildlife and sports photographers. Because it’s capable of shooting 10 frames per second for up to 200 consecutive RAW photos, it generates data incredibly fast.

To manage that load, the D500 features a mixed dual memory card slot system: Slot 1 is for CFexpress Type B (via a firmware update) and Slot 2 is for standard UHS-II SDXC cards.

Navigating these two different formats — especially considering the massive firmware upgrade Nikon issued after the camera was released — can be frustrating. If you put the wrong cards in, or configure the slots incorrectly in the menu, you will instantly cripple the camera’s ability to clear its buffer. Here is a practical look at exactly how I manage this dual-slot bottleneck and match card speeds to the camera’s actual hardware limits.

Quick recommendations

If you just want to grab a reliable card and get out shooting, these are the formats I recommend. Based on my independent memory card speed tests, these provide the sustained write speeds necessary to keep the D500’s buffer clearing quickly without forcing you to overpay for bleeding-edge speeds the camera physically cannot use.

• Slot 1: CFexpress Type B
• Slot 2: SDXC V90 UHS-II
• Dual CFexpress B / SDXC UHS-II Memory Card Reader

What memory cards the D500 takes

Slot 1: The XQD vs CFexpress bottleneck

If you look at the physical manual that came in the box with the D500, you will see Slot 1 labeled exclusively as an “XQD” slot. For a modern workflow, though, I skip XQD cards entirely.

XQD is a legacy format. The cards are expensive, max out around 400 MB/s, and are largely out of production. The modern standard is CFexpress Type B, which utilizes the exact same physical form factor but is capable of blistering write speeds over 1500 MB/s.

By upgrading the camera to firmware version 1.30 or newer, Slot 1 will natively accept CFexpress Type B cards¹. Not only will this maximize how fast the D500 clears its burst buffer, but it presents a much smarter financial investment. If you ever upgrade to a modern mirrorless flagship like the Nikon Z8, your CFexpress cards will carry right over.

There’s a catch with the update itself. A D500 still on older firmware can’t read a CFexpress card at all, so you can’t install the update from one. Copy the firmware file to the root directory of an SD card (or an XQD card) that you’ve formatted in the camera, put it in the slot the camera is currently using as the primary slot, then run Firmware version in the Setup Menu.

Heads up! Make sure to get CFexpress Type B. CFexpress cards come in three completely different physical sizes (Type A, B, and C) that are not interchangeable. A CFexpress Type A card (commonly used by Sony) is physically smaller and will not fit in your D500. Make sure “Type B” is printed on the label.

Should you buy a CFexpress 4.0 card for the D500?

The CFexpress market is currently transitioning from the older 2.0 spec to the newer, twice-as-fast 4.0 spec. Because the cards look identical, navigating this shift is actually a great opportunity to save some cash if you know what to look for.

The Nikon D500 is a CFexpress 2.0 camera. It physically lacks the PCIe Gen 4 hardware required to hit the newer 4.0 speeds. This is a hardware limitation that cannot be changed with a firmware update.

Because the CFexpress standard is backward compatible, you can put a bleeding-edge 4.0 card into the D500, and it will work flawlessly. The camera simply throttles that card down to 2.0 speeds. While you won’t see an in-camera performance bump from a 4.0 card, this backward compatibility opens up some opportunities for smart buying.

In a perfectly logical market, you’d just buy the cheapest 2.0 card you could find. But it’s not that simple. Because manufacturers are aggressively shifting their production lines to the new standard, newer 4.0 cards are sometimes actually cheaper and more readily available than the legacy 2.0 cards they replaced. In a market distortion due to algorithmic pricing based on the limited availability of legacy stock, I’ve even seen older 2.0 cards show up at massively inflated prices that are more expensive than the newer, faster 4.0 replacements.

So, my rule of thumb is to look at the sustained write speeds and go with whatever is cheaper, regardless of whether the label says 2.0 or 4.0. If you spot a 4.0 card for the same price or cheaper than its 2.0 equivalent, grabbing the newer version is a fantastic win. You keep extra money in your pocket today, and as a bonus, you unlock drastically faster desktop offload speeds when you get back to your desk (provided you pair it with a USB 4.0 memory card reader).

Because the D500 produces relatively small 20.9-megapixel RAW files, you don’t need to spend top dollar on a cinema-grade card. Here are excellent, highly-rated options that easily clear the camera’s maximum bottleneck requirements:

Slot 2: SD card compatibility & how to save money

Slot 2 takes standard SD, SDHC, or SDXC cards, and it’s a UHS-II slot, so it can use the extra row of pins on UHS-II cards. UHS-I cards still work fine in it — they just run at UHS-I speeds. If you only shoot photos occasionally, or strictly use Slot 2 as an emergency overflow drive, you do not strictly need to buy a premium V90 UHS-II SD card.

The highest video requirement on the D500 is 4K UHD at 30p, which generates a maximum bitrate of 144 Mbps. Because 144 Megabits equals exactly 18 Megabytes per second, a standard V30 UHS-I SD card is fast enough to record 4K video without dropping frames.

If you are on a budget, buy a fast CFexpress Type B card for Slot 1, and save your money by putting an inexpensive V30 card in Slot 2. However, if you do this, you must be extremely careful about how you configure the dual-slot behavior in the menu.

The dual-slot bottleneck trap

While utilizing dual cards gives you excellent data management flexibility, a modern CFexpress Type B card in Slot 1 can sustain write speeds over 1400 MB/s, while even the absolute fastest UHS-II V90 SD card in Slot 2 will max out at roughly 300 MB/s. This creates a massive performance gap.

If you configure the D500 to shoot in Backup Mode (writing duplicate RAW files to both cards simultaneously), the camera cannot clear its internal buffer until the photo is written to both locations. Because the SD card is physically much slower, the entire camera will instantly bottleneck to the speed of the SD card, completely negating the expensive speed advantage of your CFexpress card.

To avoid this buffer choke while shooting fast-paced sports or wildlife, I highly recommend configuring the slots to RAW / JPEG (saving the large RAW to the fast CFexpress card and a smaller JPEG to the SD card) or using Slot 2 strictly as an Overflow drive.

The golden rule: Formatting & quirks

My absolute golden rule for memory cards is to always format them inside the camera before a shoot to ensure the file system matches the D500’s exact specifications.

You can find the standard format tool in the yellow Setup Menu (Wrench Icon > Format memory card). You can also use the incredibly handy two-button shortcut by holding down the Mode button and the Delete button (both have small red “Format” labels next to them) simultaneously.

The Formatting Quirk: When you go to format your new CFexpress memory card using the camera’s menu, the interface will still say “Format XQD card” even after the firmware upgrade. This is just a menu text oversight by Nikon and does not affect the actual formatting process.

If you accidentally format the wrong card in the field, stop shooting immediately. Most cameras perform a “high-level format” that simply wipes the directory index but leaves the actual image data untouched. As long as you don’t write new photos over that invisible data, you can usually recover your deleted photos using a desktop recovery tool later.

If your SD or CFexpress card begins to act sluggishly or throw read errors over time, an in-camera format may not be enough. You should connect the card to your computer and execute a full format instead of a quick format using a dedicated utility tool to properly wipe and restore the flash memory.

Notes & References:

1. Nikon originally launched the D500 with an XQD-only slot. Compatibility with the much faster CFexpress Type B format was added post-release via a major firmware update. [↩︎]