FancyCache: a secondary memory cache for Windows

Martin Brinkmann
Mar 17, 2013
Updated • Nov 4, 2013
Software, Windows software

FancyCache is a new caching product for the Windows operating system that introduces a couple of interesting features that users may find helpful. I'd first like to note that it is currently available as a beta version that uses keyfiles for licenses. These licenses expire after 180 days, but since you do not need to register to download a keyfile, it should not be a problem right now. It is however not clear if the product will be offered for free once it is out of beta or if it will only be available as a commercial product then.

Update: The product has been renamed to PrimoCache. It is still listed as a beta product by the company developing it. A 90-day trial is available for download.

The basic idea behind FancyCache is to use system memory as a cache. That does not sound too spectacular at first, but there are situations where this may come in handy.

  1. If you have 4 Gigabyte or more RAM installed and run a 32-bit version of Windows, you may have noticed that part of the RAM is not really used by the system. With FancyCache, you can utilize the "invisible memory" on your PC for caching purposes so that it is put to use.
  2. It can extend the life of Solid State Drives by using something that is called Defer Write. What this does basically is consolidate writes to the same address so that writes to the SSD are reduced as a consequence.
  3. Improve the performance of the drive under certain circumstances, for instance when write-heavy applications are running.

FancyCache is available in two different editions. The disk edition implements the cache for hard drives, the volume edition for partitions. Once you have installed the program on your system and restarted the PC, you need to download the latest available license file from the official forum. Download the key file to your system and launch the application afterwards.

Click on the register button in the interface, switch to "Activate using a license key file", click on browse next to key file and select the file that you have just downloaded. You need to restart the computer a second time before the program is registered correctly.

To activate the cache for a drive or partition, select it in the list in the program window. You can configure the cache before you enable it, select the cache size for instance (this will be taken from system memory), the block size, algorithm, and whether you want a read and write caching strategy or only read or write caching.

Defer Write needs to be enabled separately, and the important figure here is latency. It determines the time writes are consolidated before written to the system. Note that data loss may occur if the computer is powered down for whatever reason in that time.

You can also enable a Level-2 caching here which works very similar to Readyboost but is more flexible in regards to the drive that you can select for that purpose. The program ships with a performance monitor that you can use to test various configurations.


FancyCache is an interesting program for users of 32-bit Windows systems with 4 or more Gigabyte of RAM, for PCs with Solid State Drives, and applications that perform many write operations on the system.

The two downsides currently are the unclear licensing situation after the program is released as a stable version, and the many restarts that it requires. Besides requiring restarts after installation and registration with a license key, it also may require a restart when you make changes to the configuration.


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  1. Stefan S. said on March 21, 2013 at 12:46 pm

    I think this is the typical scenario of the early adopters giving it a try and helping the developers establish a stable enough version. I am not sure that I would trust this software to play around with my RAM just like that. Anything that involves partioning and caching processes is a delicate issue. I like the speed improvements that FancyCache promises but I think I will wait until a more stable version.

  2. phil said on March 19, 2013 at 4:28 am

    This reminds of eBoostr I was once beta testing.

  3. RED-404 said on March 18, 2013 at 4:28 am

    I have been running this for almost a year and I have some notes for you.

    1. BUG: There is currently a known and rather large memory leak, if use FancyCache in Read/Wright or Wright-Only modes. Basically once the L1 cache is filled It will overflow and continue to fill your memory. It’s unlikely you will lose any data unless you have Deferred Write set excessively high.

    !!!Until this is fixed I recommend only using it in Read-Only mode.!!!

    2. The cache is non-persistent and is rebuilt from scratch after every reboot. I think they are currently rewriting the core of fancy cache to allow persistent cache. This and the memory leak are why they haven’t had an update in a long time.

    Given that, I still recommend it. It works quite well In Read-Only mode If you don’t reboot often.

  4. Gonzo said on March 17, 2013 at 4:11 pm

    Take heed! Moving cache to memory can be a problem with Windows Updates that require a reboot. If you’re 32 bit OS isn’t recognizing all of your memory then I’d suggest partitioning it for use as a Page File.

    Partitioning memory is much safer and more effective with Linux imo.

  5. beemeeup said on March 17, 2013 at 2:50 pm

    FancyCache is similar to Windows ReadyBoost, but operates on the block level rather than the file level. The speed improvements are tremendous since all caches are stored in RAM, and RAM is faster than the fastest SSDs by about the same amount that the fastest SSDs are faster than floppy disks.

    People often say that there isn’t any real difference between DDR3-1600 and DDR3-2133, and for many things this would be true, but with FancyCache this couldn’t be more wrong. Here’s a review of FancyCache operating at different RAM speeds:

    The more RAM you have the better, and the longer you run FancyCache the faster your system will be. Long gone are the days when a fresh install of Windows is faster than an old installation with caches fine-tuned over a long period of time.

    1. beemeeup said on March 17, 2013 at 3:27 pm

      P.S. The “Defer Write” function is super awesome, especially if you have an SSD.
      SSDs always have excellent random and sequential reads. Sequential writes are often very good as well. But random writes have always been the slowest factor by a noticeable margin, which is unfortunate since many small random writes occur far, far more often than large sequential writes. What Defer Write does is basically lump all those tiny random writes in RAM, and then writes it to the SSD as one sequential operation. Now your random writes are basically as fast as your sequential writes.

      The downside as mentioned is that if power is suddenly cut, the writes stored in the cache are lost, but for me this is an infinitesimally small risk, since I can’t recall the last time my power went out smack dab in the middle of a critical write operation, and even if it did, my PC runs on a UPS which gives me about 10 minutes of operation time. More than enough time to flush the caches and shutdown safely. Laptops wouldn’t have this problem either since they’re already equipped with batteries.

  6. Karl J. Gephart said on March 17, 2013 at 7:33 am

    I’m assuming there’s no need for the program for 64-bit Win 7 with 4GB RAM?

    1. Martin Brinkmann said on March 17, 2013 at 8:01 am

      Not if you do not need the other functionality it makes available.

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