# HDD/SSD speed question **URL:** \ **Category:** Factual Questions\ **Created:** [January 20, 2013, 11:05pm UTC](https://boards.straightdope.com/t/hdd-ssd-speed-question/647843 "2013-01-20T23:05:18Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![Nobody](https://avatars.discourse-cdn.com/v4/letter/n/94ad74/32.png) [@Nobody](https://boards.straightdope.com/u/Nobody)\ **Post date:** [January 20, 2013, 11:05pm UTC](https://boards.straightdope.com/t/hdd-ssd-speed-question/647843/1 "2013-01-20T23:05:18Z")
My wife’s computer only has SATA 2.0 ports. I bought a PCIe card that has two SATA 3.0 ports. My wife doesn’t have any SATA 3.0 drives yet, but to make sure that there was no problem with the card I connected her SATA 2.0 HDD and SATA 2.0 SSD. Before and after I did this I ran a benchmark on the drives to test their speeds. After I connected them to the card the Sequential Writing and Reading, and the Random Reading speeds for both drives went up, but the Buffered Writing and Reading speeds went down (this is on a Windows 7 32bit OS). I’m guessing that increasing the buffer size will increase buffer speed, but I wonder why it went down in the first place. Especially since non-buffered speeds increased. It’s not really important, but I am curious. Thank you. ---
**Author:** ![Nobody](https://avatars.discourse-cdn.com/v4/letter/n/94ad74/32.png) [@Nobody](https://boards.straightdope.com/u/Nobody)\ **Post date:** [January 21, 2013, 2:38am UTC](https://boards.straightdope.com/t/hdd-ssd-speed-question/647843/2 "2013-01-21T02:38:07Z")
HDD Speeds Sequential Write (2.0) 31.89 MBps (3.0) 50.52 MBps Sequential Read (2.0) 34.82 MBps (3.0) 42.25 MBps Buffered Write (2.0) 167.11 MBps (3.0) 103.79 MBps Buffered Read (2.0) 192.11 MBps (3.0) 178.20 MBps Random Read (2.0) 41 MBps (3.0) 81 MBps Any idea why buffered speeds got slower? ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [January 21, 2013, 2:49am UTC](https://boards.straightdope.com/t/hdd-ssd-speed-question/647843/3 "2013-01-21T02:49:58Z")
only thing I can think of is that the PCIe card you bought doesn’t support AHCI or has some added latency vs. the integrated SATA controller. ---
**Author:** ![Nobody](https://avatars.discourse-cdn.com/v4/letter/n/94ad74/32.png) [@Nobody](https://boards.straightdope.com/u/Nobody)\ **Post date:** [January 21, 2013, 2:56am UTC](https://boards.straightdope.com/t/hdd-ssd-speed-question/647843/4 "2013-01-21T02:56:47Z")
Actually, AHCI is the only mode it supports, but I do remember reading about a little latency due to a bridge chip on the card. If that’s it, it’s funny that it would only effect buffered speeds, but that might be it. ---
**Author:** ![deltasigma](https://avatars.discourse-cdn.com/v4/letter/d/e5b9ba/32.png) [@deltasigma](https://boards.straightdope.com/u/deltasigma)\ **Post date:** [January 21, 2013, 4:34am UTC](https://boards.straightdope.com/t/hdd-ssd-speed-question/647843/5 "2013-01-21T04:34:11Z")
I looked up the difference between SATA 2 and 3 and it may have to do with [this](http://en.wikipedia.org/wiki/Native_Command_Queuing). Native Command Queuing. That would explain the huge drop in write efficiency since the PCI-e card is expecting the drive itself to optimize head movement. ---
**Author:** ![Nobody](https://avatars.discourse-cdn.com/v4/letter/n/94ad74/32.png) [@Nobody](https://boards.straightdope.com/u/Nobody)\ **Post date:** [January 21, 2013, 7:08am UTC](https://boards.straightdope.com/t/hdd-ssd-speed-question/647843/6 "2013-01-21T07:08:51Z")
I can’t say for certain, but I’m pretty sure that NCQ mode would have been on when the drives were plugged into the integerated SATA ports. But I can easily check if NCQ is currently on. ---
**Author:** ![Dog80](https://avatars.discourse-cdn.com/v4/letter/d/6bbea6/32.png) [@Dog80](https://boards.straightdope.com/u/Dog80)\ **Post date:** [January 21, 2013, 7:16am UTC](https://boards.straightdope.com/t/hdd-ssd-speed-question/647843/7 "2013-01-21T07:16:00Z")
You can search for updated firmwares for the SSD and the PCI card and the motherboard, but if I were you I wouldn’t bother. I wouldn’t even bother installing the SATA 3 card in the first place. ---
**Author:** ![Nobody](https://avatars.discourse-cdn.com/v4/letter/n/94ad74/32.png) [@Nobody](https://boards.straightdope.com/u/Nobody)\ **Post date:** [January 21, 2013, 7:35am UTC](https://boards.straightdope.com/t/hdd-ssd-speed-question/647843/8 "2013-01-21T07:35:56Z")
Well, at today’s prices, a full fledged SSD to replace her hard drive is out of the question. The SSD is a Corsair Accelerator. Although it’s not being used at one at the moment, its purpose is to cache a hard drive so that you can cheaply boost your drive speed to that of an SSD. It made a HUGE difference in boot speed, but that was about it. But I’m thinking if I get a SATA 3.0 SSD to cache her hard drive, the speed improvement overall should be much more noticeable, because not only will the drive be faster, but the data transfers will be faster as well. ---
**Author:** ![deltasigma](https://avatars.discourse-cdn.com/v4/letter/d/e5b9ba/32.png) [@deltasigma](https://boards.straightdope.com/u/deltasigma)\ **Post date:** [January 21, 2013, 7:42am UTC](https://boards.straightdope.com/t/hdd-ssd-speed-question/647843/9 "2013-01-21T07:42:45Z")
OK, maybe I’m just lost, but isn’t NCQ only for SATA 3? So a SATA 2 drive isn’t going to have it. That was my point - as least I thought it was. 😕 As for SSD’s, NCQ won’t/shouldn’t matter since there are, obviously, no read/write heads involved. Now as to what other differences there are that may impact an SSD, IDK, but NCQ seems to be the main one that I saw listed in wikipedia. edit: [oops, never mind about that read/write head stuff](http://en.wikipedia.org/wiki/Native_Command_Queuing#NCQ_in_solid-state_drives) > [@](#): > > NCQ in solid-state drives > > NCQ is also used in newer solid-state drives where the drive encounters latency on the host, rather than the other way around. For example, Intel’s X25-E Extreme solid-state drive uses NCQ to ensure that the drive has commands to process while the host system is busy processing CPU tasks. [3] > > NCQ also enables the SSD controller to complete commands concurrently (or partly concurrently, for example using pipelines) where the internal organisation of the device enables such processing. > > For example, the SandForce 1200[4] based OCZ Vertex II 50GB drive running on a Dell Perc 5i (which doesn’t support SATA NCQ) delivers about 7,000 4k IOPS (50% write) at a controller queue depth of 32 IOs. Moving the drive to the similar Dell Perc 6i (which does support SATA NCQ) increases this to over 14,000 IOPS on the same basis. ---
**Author:** ![Dog80](https://avatars.discourse-cdn.com/v4/letter/d/6bbea6/32.png) [@Dog80](https://boards.straightdope.com/u/Dog80)\ **Post date:** [January 21, 2013, 10:49am UTC](https://boards.straightdope.com/t/hdd-ssd-speed-question/647843/10 "2013-01-21T10:49:50Z")
> [@Nobody](#): > > Well, at today’s prices, a full fledged SSD to replace her hard drive is out of the question. > > The SSD is a Corsair Accelerator. Although it’s not being used at one at the moment, its purpose is to cache a hard drive so that you can cheaply boost your drive speed to that of an SSD. It made a HUGE difference in boot speed, but that was about it. > > But I’m thinking if I get a SATA 3.0 SSD to cache her hard drive, the speed improvement overall should be much more noticeable, because not only will the drive be faster, but the data transfers will be faster as well. You can find 128GB SSDs for about $100. It can easily hold the OS and all applications and there will be plenty of space left. Move your videos, music and photos on a regular HD and you’re done. And once you have a proper SSD, the real-world difference between SATA 2 and 3 will be negligible. I have installed SSDs on ancient Windows XP machines with SATA 1 and the boost in performance is phenomenal. ---
**Author:** ![Nobody](https://avatars.discourse-cdn.com/v4/letter/n/94ad74/32.png) [@Nobody](https://boards.straightdope.com/u/Nobody)\ **Post date:** [January 21, 2013, 12:43pm UTC](https://boards.straightdope.com/t/hdd-ssd-speed-question/647843/11 "2013-01-21T12:43:30Z")
Thanks, but her hard drive is 500GB. I don’t want to get anything smaller. ---
**Author:** ![deltasigma](https://avatars.discourse-cdn.com/v4/letter/d/e5b9ba/32.png) [@deltasigma](https://boards.straightdope.com/u/deltasigma)\ **Post date:** [January 21, 2013, 1:34pm UTC](https://boards.straightdope.com/t/hdd-ssd-speed-question/647843/12 "2013-01-21T13:34:57Z")
It’s really a waste to use an SSD just for storage and honestly, you should have partitioned the 500g drive into boot and storage sections anyway. I have 4 normal PC’s and 4 servers. 3 of the PC’s have SSD’s and none are bigger than 128g. The only machine where that’s an issue for me is my main office rig where I tend to download and save to default windows folders. So maybe if that is your wife’s situation, I would go with a 256g primary SSD and use the 500g for auxiliary storage. Or better yet, take the money you’ll save on getting the smaller SSD and buy a 2-3 terabyte HDD and have plenty of backup space. ---
**Author:** ![Nobody](https://avatars.discourse-cdn.com/v4/letter/n/94ad74/32.png) [@Nobody](https://boards.straightdope.com/u/Nobody)\ **Post date:** [January 21, 2013, 6:24pm UTC](https://boards.straightdope.com/t/hdd-ssd-speed-question/647843/13 "2013-01-21T18:24:07Z")
Edit. Never-mind. Anyway, I think we’re getting away from GQ, so I’ll just thank everybody for their help and advice.