HP EX900 SSD Review: HMB Makes DRAMless Better

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The EX900 is a good SSD for casual users, but it has a pricing problem that needs to be addressed before we can recommend it.
Except "casual users" don't need an NVMe SSD, and would likely be better off paying less for a SATA one. In fact, I'm not convinced that most people will see much benefit from going with NVMe. Maybe things will load slightly faster, but it's questionable whether the real world performance gains are significant enough to justify paying 50-100% more for a given amount of storage. In my opinion, the biggest thing limiting SSDs right now is still cost for capacity, rather than performance, and SATA SSDs are a lot better in that regard.

And if the story here is that this drive is intended as an upgrade for SATA SSD users, it would be nice to see a SATA SSD included in the benchmarks. Of course, the SSD reviews here focus a bit too much on synthetic benchmarks anyway. Sequential performance at QD128 might be relevant to some very specific usage scenarios, but probably isn't useful for the vast majority of people shopping for SSDs.

And the "real world" benchmarks that are here all seem pretty terrible. If there's any performance difference between these drives, the PCMark 8 storage tests certainly don't show it. When nearly all the results are within 1-2% of one another, what exactly does that tell anyone about the performance of these drives? And how do these results even relate to what actual performance will be like in these applications? What specific tasks within the software is PCMark even testing? It's certainly not explained in the review, or even in the "How We Test HDDs and SSDs" article for that matter. Are they loading files, saving files? If so, what are the specifics of those files? With none of that explained, these "real world" benchmarks become little more than extremely abstract synthetics. How does something like 887MB of data read and 28MB of data written in Battlefield 3 relate to what actual load times might be like in that game? It results in 132 seconds of the drive doing something, but what? And with all the results from the slowest to the fastest drive being within 1 second of one another, how is that information even remotely relevant? Even the recently reviewed Crucial MX500 SATA drive averaged performance within 1% of this drive's results across PCMark 8's "real world" storage tests. If these tests are in fact representative of the real world, then there's little point in paying significantly more for NVMe for virtually identical performance. I'm sure there will be larger differences for things like bulk-copying directories of files within Windows Explorer, or installing software, but these reviews don't really provide any real world examples of that either.

Why not test some actual real world load times in applications and games? Load up a bunch of image files in Photoshop or videos in Premiere. Load up some levels in popular games, while using disk monitoring software to accurately track when the operation is complete. Test the time it takes Windows to load from a cold boot, or to return from hibernation. Install an application and run a malware scan. Such results would be far more representative of the real world than what PCmark's storage tests provide. And if the results still show no significant difference between a SATA SSD and an NVMe one in many of these common scenarios, then point that out. As it is, these reviews seem to do a good job testing synthetic operations, but the real-world tests are quite lacking. I get the impression that PCMark is being used for simplicity of testing, rather than providing any relevant results, and the fact that only a couple sentences are used to vaguely describe a drive's supposed performance across 10 applications and games should show how relevant the reviewer considers the results to be.

That process relies heavily on speedy DRAM, but memory is expensive. HMB technology allows SSD manufacturers to remove the DRAM on the SSD and use a small amount of your system memory (RAM) to achieve similar results. In general, a 512GB SSD will consume 512MB of system memory, but the dynamic cache grows based on the amount of data stored on the SSD. The amount of data used by HMB is a pittance compared to the amount of RAM in a typical system.
How much does 512MB of DRAM actually add to the cost of an SSD? Going by the cost of DDR4 system RAM modules, that works out to around $5 to $7 at retail, even ignoring the added costs of those modules. There will undoubtedly be other circuitry required for reading that memory on the drive as well, but I doubt that cutting out the DRAM is likely to save much more than $5 off the cost of a 500GB drive. It kind of makes DRAMless SSDs seem a bit pointless when removing the onboard memory likely only results in such a small price reduction. Maybe at the extreme low-end, when trying to shave a few extra dollars off a $50 drive it could be useful, but this isn't a $50 drive. Even the 120GB version is in the same price range as many SATA SSDs with double the capacity.

And as for the amount of system RAM being a "pittance", I would argue against that, at least for many usage scenarios. With RAM being expensive right now, many people building on a budget don't want to put more than 8GB into their system for the time being. For something like gaming, or many other usage scenarios where users are coming close to topping out 8GB of system memory, that can be significant. After accounting for the couple gigabytes used by the OS and background tasks, 512MBs could add up to nearly 10% of the memory available to applications and games. Sure, a user could move up to 16GB, but that will cost another $80-$100+, and most of that extra RAM probably won't be getting utilized any time soon in most systems. For someone with limited system RAM, paying an extra $5 or so for an SSD to have its own onboard memory could easily be the more reasonable option.


Aug 18, 2016
Even with the high cost of RAM these days, I'm not convinced the saving
of a few dollars is worth it...................


Jan 25, 2015
I wrote this article before the 970 series was available.

"Why not test some actual real world load times in applications and games?"

I'm working on that now.

Olle P

Apr 7, 2010
My thought also. If the EX900 is meant to draw consumers from low end 2.5" SATA drives it would be suitable to have such drives in the comparison (and a regular HDD thrown in for good measure).

Where I live (in Sweden) a low end 500 GB 2.5" SATA SSD is 8-10 times more expensive per GB than a 2 TB HDD.
The NVMe versions are some additional 20% up in price compared to 2.5".
Is the benefits worth it?
If you're low on space for another 2.5" drive, then sure, but that's rarely a problem.
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