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I've bought an SD card today for my phot frame, but when I inserted it into my notebook I saw I could use it for ReadyBoost.

Some background

I'm a .net developer, using VMs and developing web applications (and Sharepoint). I use an HP notebook machine with Core 2 Duo 2GHz + 4GB RAM + 320 7200 HD. I simultaneously run

  • Visual Studio 2010 with some plugins
  • SQL Server
  • Firefox with at least 10 tabs
  • Chrome with about 5 tabs
  • IIS
  • VM with Server 2008 machine
  • Sharepoint

and occasionally also Photoshop and some InDesign as well. So I don't let my machine have a break. :D


If I buy myself some really fast SDHC card (like SanDisk 16GB Extreme 30MB/s - is there anything faster) and use it with my Windows 7 ReadyBoost, will I see any performance gain? Is it going to work something similar to Seagate's HybridDrive Momentus with 4GB of solid state drive?

What could I actually expect if I do put this card into my machine? And what would be recommended size?


I guess redirecting page file to it would speed up the system. Some VM machines on it would probably run faster as well because they could run parallel to HD host system I guess. Am I right or wrong?

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migrated from Oct 9 '10 at 18:25

This question came from our site for system and network administrators.

Any time you eliminate hard drive contention the system will benefit. If the system, page file, vm file are all on the same hard drive, they all will fight for that resource. If you want something like Momentus, you may want to look at SilverStone's HDDBoost… it's speed is between a HD & SSD. The only thing that will give you SSD speeds is an SSD or RAM drive (like an i-RAM or similar – Scott McClenning Oct 9 '10 at 22:44
Here is another question about ReadyBoost to consider because it talks about how it works and performance.… – Scott McClenning Oct 10 '10 at 3:12
up vote 5 down vote accepted

ReadyBoost is a reading file cache, it is not an extension of virtual memory, that is based on the fact Flash memory has effectively zero seek time to cache small files (because Flash memory is also slower at sustained write that you HDD).

What ReadyBoost also does is provide more space for the Windows Super Fetch function, if you don't have any ReadyBoost enabled device connected this will still be happening in your spare RAM; so you see best performance gains if you have a low quantity of RAM, where not using RB means the SF cache has to be dropped when the RAM is needed by software.

In response to comments on studiohack's answer:
There's no worry about syncing, it's a read cache and basically if the file's not ready in the cache Windows just pulls it from the HDD instead. As an aside also note the contents of the cache are encrypted and compressed, so your data is safe from the sudden theft of the SD card.

Bottom line, using RB won't degrade performance, so it's worth trying if you've a spare card about, but with 4GiB RAM, don't expect any serious improvements.
(Although, that doesn't stop me running 16GiB of RB with 4GiB RAM!)

My answer to ReadyBoost - How much space needed? may also prove useful.

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great answer, i was somewhat lost with some of the ReadyBoost questions, I'm not an expert :) – studiohack Oct 9 '10 at 21:20
What about the fact that I'm utilizing majority of my system RAM because I'm running host + VMs which makes it basically quite full. Based on your info this means that I don't have much spare RAM for ReadyBoost so adding an SD card could still be good wouldn't it? – Robert Koritnik Oct 10 '10 at 10:54
@Robert, could be, really depends on what you are doing on the host - remember the main improvement is when loading programs / files. So if you load everything up and then leave things fairly static it might not really help. And RB won't help at all if you start paging - even if every file you have to load is cached, if something ends up writing to HDD the entire process will be awfully slow. Frankly, the best thing you can do is plug in any spare SD or USB stick and test; it doesn't destroy any current contents, but obviously the RB cache size is limited to free space. – DMA57361 Oct 10 '10 at 16:47
Just inserted SDHC (Class 4 though) card in and I'll completely format it ans see what happens. Maybe it'll convince me to buy a Class 10 16GB SDHC. Who knows. ;) – Robert Koritnik Oct 13 '10 at 11:17


ReadyBoost impacts application loading, closing and switching time, but CPU intensive tasks aren't impacted nearly as much. As such, most of our conventional benchmarks, even when running with only 512MB of memory, don't serve as a good benchmark for ReadyBoost. If your system has so little memory that it is swapping to disk while running a single task then you're in trouble, and ReadyBoost isn't going to save you.

Source (and more info) @

As for the SD card size, the bigger the better. The most important factor, however, is the speed of the card.

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So would it work similarly as Seagates Momentus Hybrid drive? So running VMs would probably benefit from this SDHC, because Windows would determine, that these files are frequently used (or something) and use them... May synching be a problem? Slower shutdown (due to saving state back to HD)? – Robert Koritnik Oct 9 '10 at 20:35
@Robert: Frankly, I don't know anything about the SeagateMomentus HDD...Your comment is vague, can you clarify? – studiohack Oct 9 '10 at 20:37
Clarifying: If Windows is using ReadyBoost, data is not completely sync'd (I suppose, otherwise there would be no speed increase) and at some point it has to be sync'd. Probably at windows shutdown. Is this correct? – Robert Koritnik Oct 9 '10 at 20:49
Regarding VM: Would it be better to run VM from SD card and not use ReadyBoost or run it from HD and use ReadyBoost? SD is larger than VM size. – Robert Koritnik Oct 9 '10 at 20:49
@studiohack: I guess I could move my pagefile (virtual memory) to SD card if I wanted to. So I don't really see it that way, but I may be wrong. the thing is this machine is a notebook where I can only have ONE hard drive. I don't want to splash out a fortune for a decent SSD (like at least 128GB) to put everything on it, but I could use a normal HD + a 64GB SDCard. The fastest I could get (probably SanDisk Extreme). I would use it as permanent storage. – Robert Koritnik Oct 10 '10 at 10:38

Running : HP Mini 210 Netbook, 750 gig hard drive, 2 gig Ram. Loaded with : Windows 7 HP Complete Install, SQL Server 2008 R2 Developer, Office Professional 2007, MySQL, PHP, Norton AV

As speed/performance became more of an issue I noted the constant offer to 'ReadyBoost' your flash drives. My search of the Web led me to believe that performance was not really enhanced and the maximum I could use was about 4 gigs, backed up by the fact that my computer said so too. Trying to partition an 8 gig Micro SDHC in to 2 to enable using one partition as a Booster and the other as a Norton & System Backup drive proved unattainable. Putting that idea aside I single partitioned the disk, formatted it using NTFS, changed the Policy to enable disk caching, made it my 'A' drive and then ran the 'ReadyBoost' option. Not only did I get the entire 8 gigs being used, I also saw my HP Mini 210 Netbook come back to life even with it's fully loaded development platform. IPI Paul...

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Was setting it as "A" drive important? Would it make any difference if you'd just keep it as it was? – Robert Koritnik Oct 10 '10 at 10:56

With a high performance laptop, I doubt that you will see much improvement. ReadyBoost is not treated as additional RAM, but is only used to cache data. Based on this earlier post, you'll see a performance increase if you have between 1 and 2 GB of RAM.

I have a laptop with 4 GB of RAM, and decided to remove the "high speed" SD card and turn off ReadyBoost. IMHO ReadyBoost seemed to slow my PC down.

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Thanks Rick. I'm just about to test this. It's true I put in a Class 4 SDHC card in, but let me see if it improves anything. I'll decide later whether it's feasible to invest into a Class 10 SDHC card of 16GB size... Since I'm currently using a 320GB HD I just wish that SSDs would be cheaper. I can't really make it work with just 128GB. I should have a larger one. And Seagate could make a hybrid with i.e. 32GB of SSD. That would make it a first class contender against SSDs. – Robert Koritnik Oct 13 '10 at 11:11

I tried putting a SanDisk Extreme Class 10 SDHC card into my ThinkPad X200s with 4GiB of RAM. There was no noticeable improvement, so I put it back into my DSLR.

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But have you tried using it as a second drive by putting on some software? Like putting on Virtual Machines and running them? – Robert Koritnik Oct 10 '10 at 10:57
@Robert: No, as I was only testing to see if it was worth me getting another card for ReadyBoost. I'm waiting for SSD on a standard single full size mini-PCIe card, for hybrid storage, or affordable high capacity SSDs. The third generation Intel SSDs should come out pretty soon. – paradroid Oct 10 '10 at 21:48
@jason: And that will make SSDs cheaper in what way? The new ones will be cheap or the old ones will be substantially cheaper? – Robert Koritnik Oct 13 '10 at 11:08
@jason: What do you mostly use your machine for? Do you think that you max out your RAM capacity? Or get close to the limit? Because I do tend to be over 3GB most of the time... – Robert Koritnik Oct 13 '10 at 11:12
@Robert: SSDs will be faster, bigger, cheaper and longer lasting, as the technology matures. I mainly use my ultraportable X200s for network stuff, Office, web browsing, Adobe Lightroom and RDPing into my server. I don't reboot very often and have lots of programs and browser tabs open at any given time. I would not be able to do with less than 4GiB or RAM very comfortably. – paradroid Oct 13 '10 at 14:09

You are all wrong. Ready boost serves to eliminate Hard disk bottlenecks wherever possible - the Ram cannot serve this function as it is a temporary open space of memory that is close to the cpu, and cannot permanently store data.

This means that if you were to, in theory, upload all the required data onto the ram, you'd have to wait on the harddisk to upload the data to the ram (and this would equal a long waiting time, possibly longer windows boot). And this is not convenient. You need another storage medium which is perfect for small random reads. Something that can always have the data stored, and aid in the lowering of load times of certain windows functions and applications.

If you want the ram to do this job, you'll have to initially load all that will be required onto the ram, meaning there is less memory available for applications to be used when opened. Even if you had 16gb ram, this is still not efficient on its own, as you will still require the slow hard drive to upload the small fragments of data that is needed to be randomly read and uploaded. The flash drive is ready and available, always, to upload small bits of data, randomly read, so that when the program launhced can quickly have available various small files rather than waiting on the slower haarddisk to perform a similar function for that application.

The ram is not a storage medium, is it the place where everything is held whilst in active usage. I think of it as the computers "thinking space". And every once in a while, you will require the hard disk storage device to load more and more files into the ram when the application or a function of the OS requires it to do so.

This is therefore, a comparison between the efficiency and speed of the hard disk vs that of the flash storage device - and these two serve totally different functions to the ram. You cannot therefore expect the ram to be a better alternative or a better way to increase performance (although this is providing that you have installed more than enough ram for your computer to load applications without resorting to a paging file).

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Sorry, but your analysis is incorrect. The ReadyBoost cache contents are not trusted across boots. So anything that RB is going to be cacheing has to be read from the hard drive and written to the RB device anew on each boot, just as it would be if it was cached in RAM (as SuperFetch will do, if the RAM is available). In fact, due to the way the RB cache is encrypted (with a per-boot session key), each new boot couldn't read the old boot's RB cache even if it wanted to. – Jamie Hanrahan Jan 28 at 4:27

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