I'm building my first PC for 5 years, for general use and also for photo-editing in Photoshop (with large files). Cooling will be totally passive: Core i7 3770 processor with passive cooler, Seasonic Platinum Fanless PSU and Nofan CS-80 case. Storage is the only outstanding design issue.

I've ruled out having an NAS, and my current thoughts are to have 3 internal drives:

• a Plextor PX-256M5P SSD for system files, programs and general data
• a 500 GB - 1Tb HDD of some kind (Caviar Green?) for storing images
• a 1Tb - 2Tb HDD (again Caviar Green?) for the continuous backup of the other 2 drives (supplemented by periodic off-line backups)

I'm finding the reliability figures for modern HDDs (and particularly for the Caviar Green HDDs) very disappointing, and am struggling find a drive that strikes a good balance between reliability, performance and speed.

It seems counterintuitive, but I'm wondering whether a 750GB Seagate Momentus XT (ST750LX003) would be preferable to a Caviar Green - particularly since the system is to be passively cooled. I know that for this application the SSD element of the drive will be of little benefit, but the general specifications are very good, and reliability is repoted to be excellent. I haven't been able to find information or benchmarks to provide a direct comparison - all the reviews now seem to be for SSDs, and not for HDDs - but the following comparisons make me think that it's not that crazy an idea:

_______________Momentus XT___Caviar Green
________________ST750LX003____WD10EZRX

Cache_______________32MB_________64MB
RPM_________________7200_________5900?
Seek____-__Read______11ms__________?
________-__Write_____13ms___________?
Noise____-__Idle_______23dB_________23dB
________-__Seek______26dB______24dB_/_27dB
Power___-__Idle_______1.1W_________2W
________-__Seek______1.3W_________4W
Warranty___________3_years______2_years

I would be grateful for any thoughts in general, and any information on how the performance of the Seagate would compare with that of the Caviar Green.

The Momentus has poor $/GB and is a 2.5" drive most likely designed for mobile applications. Desktop use may not appreciate frequent head parking and such precautions mobile drive firmware has in place, either wearing down the drive unnecessarily or affecting response times.

The Green worries have been part FUD, so take with a pinch of salt.

If you want a longer warranty, get a WD Red. Solid choice for silence according to SPCR review (and power efficiency should deal with cooling) and for the price of a 750 Momentus XT you can get the 3 TB Red if you want - or save some money and get the 2 GB one.

Totally passive cooling is really iffy on HDDs in my experience, unless you can get heatpipes or similar conductive elements in place.

Thank you very much for the response. I take your point regarding the problems that may arise due to frequent head parking etc..

I had seriously considered a WD Red drive, but was concerned that it might not be suitable for a desktop operation. Some of the special features of Reds appear to be for the good (eg. reliability and power consumption), and some seem not to matter either way (streaming support and power management support within an NAS). But Reds apply TLER (appropriate for RAID, but not for a non-RAID environment), and there may be other aspects of the firmware of which I'm unaware that would make them unsuitable for use in a standard desktop. Any more information / reassurance about these aspects would be very much appreciated.

I wouldn't worry too much about TLER. There may even be a way to switch it on and off. It's only relevant if your drive starts to fail (how long will it attempt rescue), and that's what you have backups and monitoring for.

Red is fine for desktop. So many people are just scared of the unknown - you can read it all here on SPCR forums.

For what it is worth: I had purchased a Momentus XT 500GB for my laptop, but dumped it because of the horrible resonances it produced (the laptop is a Lenovo T420).

Thank you very much for your comments. They have been very helpful.

I followed Das_Saunamies's suggestion, and looked into TLER in more detail. For the benefit of future readers, I will summarise what I see as the main points:

• The TLER setting implemented on RE and Red drives (that limits the time that a drive will continue to try to read a problem sector) is 7 seconds. This setting is necessary to prevent a drive that encounters a problem sector being dropping by a RAID array. If a drive is not part of a RAID array, there is no benefit to restricting the time spent trying to read a problem sector, and once the error checking is stopped, any data present in the problem sector will be lost forever (unless special tools are used). But it is debatable whether in practice a problem sector would yield up any useful data no matter how long it was given to do so, if the drive has been unable to extract the data in 7 seconds (which is time for very many attempts).
  
• WDTLER.EXE (a WD utility) can be used to permanently change or disable the TLER setting on older drives, but it does not work on modern RE and Red drives (and, according to Wikipedia, it can damage the firmware of modern drives and make them unusable).
  
• smartctl (a component of Smartmontools, available at sourceforge.net) can be used to change the TLER setting of modern drives, but the change is not "sticky" ie. it is lost when the PC is powered down or put into sleep mode.

The Momentus XT has excellent energy and noise specifications, but jerdenberg pointed out noise issues in practice. Given the enterprise level reliability of the Reds and the issues Das_Saunamies raised with using Monentus XT for this application, including frequent head parking, I've decided to get a Red drive (and decide at a later date whether to have a startup batch file to disable TLER using smartctl).

Alrighty. I'm sure it'll be fine; my approach to data is that unless there is an original, a dynamic backup and a static backup, that data does not exist. I'll worry about TLER when I see some actual issues arise.

Well said. I think we're of one mind!