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  SSD with second hard drive 
 Date Written 
Graham Strong May 19, 2014, 05:53am EDT Report Abuse
Hi guys, hope someone can help me.
I have an Acer V3-731 laptop which has two HDD bays.
Recently cloned my old drive to a Crucial M550 SSD (256GB) and that part is ok.
When I do a SSD speed test on it, everything looks good.
However, when I connect the old, formatted HDD to use for storage, the write speeds and access times of the SSD are about half - read speeds still good.
The laptop was set to ACHI previously, but a while ago had to do a Windows 7 reinstall by CD, unable to use the Acer factory restore.
Although no drivers are showing as a problem, is my SSD slow write anything to do with the wrong driver?
Many thanks

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john albrich May 19, 2014, 10:12am EDT Report Abuse
>> Re: SSD with second hard drive
I assume you've verified that by removing the HDD the performance problem disappeared?

Need to enable AHCI according to posts in multiple fora on [ slow ssd after adding hdd ]. Drivers should be there with Win7, but have to enable in BIOS/UEFI settings, and you have to follow the right install procedure.

In lesser likelihood of contributing to the problem...

Also, check boot order of drives, and make sure HDD isn't even on the "boot from" list if possible. While I wouldn't think those settings would affect post-boot performance, one never knows with all the weird firmware/software out there, esp with that unknown partition on the HDD.

Re the unknown partition on the HDD, you should be able to use either the manufacturer's HDD management tool or a freeware/donateware HDD management tool (found on multiple download sites like majorgeeks,, etc) to de-activate that partition and format the entire HDD. Just use a tool that is self-booting (e.g. from CD/DVD/thumbdrive/etc), and doesn't require going through Windows to take care of that. Make sure the disk manager handles the format type (e.g. advanced 4K/sector v. non-advanced 512/sector as needed for that particular HDD. IF your HDD is an advanced format drive (4K/sector), then some of the older managers don't handle the new 4K format.

Verify TRIM is enabled for the SSD. Although highly unlikely to be a contributor in this "it only happens when the HDD is installed" issue, TRIM needs to be enabled for the SSD regardless.

Final thought with which others might have experience (and if the AHCI didn't take care of things)...
I've never had to mix advanced format and non-advanced format HDD in a system, so I don't know if that even could cause a performance hiccup. But, IF one drive is advanced format and the other drive is non-advanced format then perhaps the system has problems with that mix.

Graham Strong May 19, 2014, 02:02pm EDT Report Abuse
>> Re: SSD with second hard drive
Thanks for your very informative reply.
I had checked most of the items you mentioned ... BUT have discovered what was causing the slow write speed and don't fully understand why?

Today, I removed the 2nd drive and to my surprise got a low write for the SSD???
Have confirmed now, 2nd hard rive has nothing to do with it, BUT if I have the laptop mains charger plugged in I can get the higher figures!
Using AS SSD benchmark tool, on mains power for sequential I get 489R / 456W but on battery 488R / 89W.

I appreciate that on battery the power is reduced, but begs the question why read is unchanged but write reduced by a fifth?

Any ideas?
Hope this information might help somebody else with similar speed issues?

Naveen Goud May 19, 2014, 05:57pm EDT Report Abuse
>> Re: SSD with second hard drive

As per my knowledge, reading on an SSD takes very little power and so SSD read abilities are intact. Write capabilities consume more power and since the laptop is running on battery, the bios of the laptop might be offering less power to the SSD so that the task can go on even though it is at a slower rate.

Hope, this makes sense!




john albrich May 19, 2014, 10:02pm EDT Report Abuse
>> Re: SSD with second hard drive
It's also possible that the laptop has drivers that change the Windows write-cache management depending on whether it's on mains or battery power.

Depending on the disk performance tool, the Windows write-cache can make a HUGE difference in drive performance "seen" by the tool. You might check the program to see if it has a 'disable write-cache' setting. For example, "Disk Thruput Tester" program gives the user a checkbox to disable Windows write-cache during the tests. This is NOT a recommendation for this test tool as I've not tried it on an SSD. I'm just pointing out the tool's write-cache handling option. <--download link <-- info link

One can also disable/enable write-caching for a specific drive via Windows Disk Manager settings. However, it should be noted, that in Win7 some measure of control is taken away from the users. Write-caching may be globally RE-enabled when the system wakes up or is rebooted. I could see Microsoft making the same true for when the laptop changes from mains to battery.
(source: In the current design of Microsoft SATA driver stack, the device write cache will be enabled after every power cycle (computer resumes or reboots). This is a by-design feature in Windows 7.

Graham Strong May 20, 2014, 06:03am EDT Report Abuse
>> Re: SSD with second hard drive
You guys are very knowledgeable ! Thanks.
I have emailed Acer asking about drivers, interesting to see what they say.

I tried two different benchmarks, the other called bench32 (or similar)? Both similar results.

I tried ticking and not, the write cache box in Windows and got slightly better results with it ticked (seems to go against other reports). Also stopped auto defrag, prefetch and superfetch too. The BIOS is very limited and not a lot can be changed. Even the video RAM is greyed out, but maybe that's because it uses an Intel B970 (with graphics integral?)

Had another problem yesterday with Control Panel - when trying to open CP, Windows Explorer crashed. Wondered if it was because I stopped all swap files (my RAM is 8Gb). Now have a small swap file (128-1024Mb) on the 2nd drive.

I fully recommend the Corsair Vengeance RAM I got, gave me a 7.7 on the Windows Experience and the Crucial HDD is 7.9 (top figure!). WOW!

It's reasurring to know why something happens, but still annoying!
Thanks again.



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