I plugged a Samsung 990 Pro 1TB NVMe into the Thunderbolt 5 port on my Lenovo ThinkPad P16 Gen 3 mobile workstation. ICYDK, TB5 promises up to 80 Gbps bandwidth. The 990 Pro is one of the fastest consumer NVMe drives money can buy. I expected fireworks. I got a firefly. Fortunately, I determined that clicking two checkboxes means 12 faster results. This comes from foregoing quick disconnect and enabling write caching. Let me explain…
Exploring: Two Checkboxes Means 12X Faster
As shown in the lead-in graphic, CrystalDiskMakr tells the ugly truth. As you can see on the left hand side, read speeds looked good. But writes are stuck in what I’d charitably call “USB 2.0 territory.” Something was very, very wrong — and it wasn’t the hardware. Results come from CrystalDiskMark 9.0.2 x64 software.
Now, look to the right, you can see that write speeds jumped significantly, while read speeds stay more or less the same. Indeed, the Thunderbolt 5 (TB5) link and Acasis TB501Pro enclosure weren’t the whole bottleneck. Sequential writes jumped from 473 to 5,943 MB/sec for a 12.6X speed boost.. Even more amazing: 4K Q1T1 writes leapt from 1.04 to 110 MB/sec, for a 105X gain.
All this came from two little checkboxes, on the Policies tab from the Properties window for the Acasis TB501Pro enclosure. Deets follow…
Two Related Settings in DevMgr Do the Trick
Here’s the 30-second procedure:
- Open Device Manager → expand Disk drives → right-click your external NVMe → select Properties → click the Policies tab.
- Switch from “Quick removal” (the default) to “Better performance.” This unlocks the write caching option that’s otherwise grayed out.
- Check the box for “Enable write caching on the device.” This is the setting that actually turns on write caching.
- Click OK, then rerun your benchmarks and enjoy the results.
Both settings are required. Selecting “Better performance” alone without the write caching checkbox won’t deliver these numbers. You need both.
Here’s the Tradeoff
Windows defaults to Quick Removal for a good reason: it protects against data loss if you yank a drive without ejecting it first. With Better Performance and write caching enabled, you must use “Safely Remove Hardware” before unplugging, or you risk losing data still sitting in the write cache.
That’s the tradeoff. For a stationary workstation drive that stays plugged in during work sessions, it’s a no-brainer. For a drive you hot-swap constantly throughout the day, think twice. I’m going for maximum speed on backups and restores, so I’ll make myself remember this tradeoff if I need to unlplug the NVMe enclosure.
The Results Could Still Be Better
I’m still of the opinion that — as I opined in my Feb 20 blog on this topic — that buying a TB5 NVMe enclosure isn’t worth the added expense. TB4 enclosures cost about US$100 less, and deliver nearly the same performance as TB5 (it’s a 10-15% difference at best). Doubling the price for a modest gain just doesn’t make sense. TB5 shines for video and networking. For storage links, not so much, because controllers basically limit links to PCIe x3/x4 levels.
That’ still true today. But I was pleased to get much more out of my rig once I made the enclosure behave more like a USB drive and less like a USB stick! Here in Windows-World you sometimes have to take your wins where you can find them…




