(from a reader mail on Dec. 28th, 2009)

"WD 750GB Scorpio Report
I've been waiting for WD10TEVT available since WD's its press release last summer. But just couldn't wait any longer, so I grabbed WD7500KEVT last week. Here's my experience with this new drive.

MacBook (Late 2008 - Unibody)
-EFI Firmware Update 1.4 Installed
-Mac OS X 10.6.2 (w/all available software updates installed as of today)
-Disabled "Drive to sleep when possible" for both AC & battery power
-Enabled "the Sudden Motion Sensor"
(Do you mean disabled it? I thought that Apple's SMS was enabled by default, and for any drive that has its own built-in shock sensor I'd disable it. Terminal command for that is sudo pmset -a sms 0 (ref: Apple doc Advanced tips for Sudden Motion Sensor). The descriptions I've seen on this drive does mention it has WD's "ShockGuard".)
(He later replied)
Thanks for your note about WD's "ShockGuard"... I meant to say "left the SMS enabled by default", but now I just made it disabled as you mentioned and see how the drive is going on.
(Reader FYI - the comments below were from before SMS was disabled.)

WD7500KEVT-00A28T0
-Revision: 01.01A01 (drive firmware version)

I replaced WD5000BEVT (one year old) with WD7500KEVT last week. I had noticed clicking noise would often occur since then. Last night, I searched web and found two blogs explained about clicking noise as follows:
mymacfixes.blogspot.com/2009/06/how-do-i-stop-clicking-noise-from-hard.html
dougitdesign.com/blogs/blog_12_08_mac-clicking-hdd-hard-drive-noise-hdapm_old.html (no longer online)
What they said is the clicking noise might be shortening the life of the HDD. (I didn't know that)
(FYI for those that missed it (and the clicking/APM issues/tips go back many years - notes on that since the PB G3 days and of course it doesn't just affect macs). There's a previous page here on OS X Notebook HD Load Cycle Counts (not limited to OS X of course) where I posted reader feedback on various notebook drive brands/models after some had wrote they were concerned over their drives racking up cycles at a rate that would have exceeded the mfr's spec (500K or 600K cycle rating IIRC) within just a few months. Although some older drive owners reported their drives had as many as 2 million+ cycles reported. And clicks are not always a sign of this - even on a drive that I'd never heard any clicks (WD 500GB Scorpio in a Vista laptop) it was reporting appx 1 load cycle every 2 minutes. That will vary by usage/settings and even drive model. Personally I've never been concerned about load cycle counts - but also have never had a drive with the infamous "click" issue either.)

So, I tried the above method (hdapm from http://mckinlay.net.nz/hdapm/), and have solved successfully. (Note: I used "hdapm disk0 254" instead of using "hdapm disk0 max" didn't work in my case.)
After all that, I checked "Load Cycle Count" with SMART Utility again.
Raw Value : 4132 (WD7500KEVT) versus 1309 (WD5000BEVT)
(Note: Before this fix, it kept increasing by more than 100 within a couple of hours.)

No more clicking noise and Load Cycle Count is not really increasing so far. I Hope this might help if there is anyone have the same issue.
BTW, Attached are benchmark results of Xbench for both drives. (I asked for info on how full each drive was at the time. (As outer tracks are fastest, drives slow as they fill.) He later replied with that info:)
BTW, I always partition off the drive into 2 volumes. (one small outer tracks for OS and apps, and the other for Data). As you requested, here's the details at the time.

WD7500KEVT
16% filled - 150GB for OS (TEST Volume)
68% filled - 600GB for DATA
Total 72% filled (out of 750GB)

WD5000BEVT
30% filled - 60GB for OS (TEST Volume)
86% filled - 440GB for DATA
Total 79% filled (out of 500GB)
(even less usage in the past, never hit 65)

(See notes above regarding drive partitions/space used)

I would say WD5000BEVT is faster, but not much difference in real usage. I'm happy with this new drive.
-Hideaki K."

The Dec. 9th news page has some earlier reader reports on the WD 750GB Scorpio (as well as the 640GB model, as some readers had a mini that could not fit the 12.5mm high 750GB Scorpio.) Most other readers didn't note any clicking issue. (But as with anything - YMMV.) To save you a click/another page loading - here's a copy. (Verbatim)
The Dec 8th news had a request for feedback from readers that are using an internal Western Digital Scorpio 640GB (9.5mm high, 5400 rpm/8MB cache) or WD Scorpio 750GB drive (12.5mm high, 5200rpm/8MB cache). [BTW - the price went up quite a bit on those since early Dec. posting - especially on the 750GB. I assume due to limited supply.] (As noted before Unibody MB/MBP models can take 12.5mm high drives, but of the pre-Unibody models only the 17in MBP can. Minis to date are still 9.5mm max.)
Previously I'd had a reader from the UK say he'd installed a 750GB in a friend/clients Mac and they had commented on drive clicking (something that has come up in the past). He was going to personally check on that but not heard back yet. (And we also discussed other tips from the past (not just APM), including disabling Apple's SMS for drives w/builtin Shock Sensor.) After getting more questions on these drives recently I thought I'd ask for feedback from other users.

Here's the replies from the last 24hrs (I'll also be adding these as reports in the drive database in the next 24hrs.)

"I'm running the WD 750GB HD (drive firmware 01.01A01) in my Macbook Pro [late 2008?] 2.66ghz (expresscard version), 8GB Ram running OS X 10.6. Runs great. No extra noise than the previous 500GB that was in there. Great having the extra space... Very happy.
I also have the 640GB in a 2Ghz Mac Mini running 10.6 server (as it's 9.5 high its the biggest that will safely go in there) This feels a bit slower than the previous WD 320GB (5400rpm).

(I asked if he'd noticed any clicking noise)
Nope - no clicking noises at all. It's a unibody model as the 750GB is a 12.5 height drive. I dont think it'll fit the older form factor ones will it? (for pre-unibody's only the 17in MBP can take 12.5mm high HDs)
I've attached screengrab of my energy saver settings. (Shows Drive Sleep enabled but system sleep set to never.)
-Alan B."

"As requested, current new system details below:
MacBook 4,1 (2.4GHz C2D, 4GB RAM, Boot ROM MB41.00C1.B00, SMC v1.31f0)
WDC WD6400BEVT-22A0RT0: (report below noted -00A0RT0)
Capacity: 640.14 GB (640,135,028,736 bytes)
Revision: 01.01A01 (drive firmware version)
Mac OS X 10.6.2
It replaced a Seagate Momentus 7200.4 ST9320423AS (7200rpm, 16MB cache) 320gb drive that was > 90% full.
The 640gb drive has been in use for a couple of months with zero issues whatsoever - it's quiet and vibe free and feels about the same in use as the >90% full 7200rpm 320gb Momentus that it replaced. (HDs get slower as they fill, outer tracks are faster) Highly recommended!
The 750gb drive you enquired of is a 12.5mm high drive, consequently it won't fit in my MacBook, else I'd have had that one!

No probs whatsoever with clicking or *anything* at all untoward.
When on battery the drive is set to spin down where possible, the display to sleep at 5mins and the computer to sleep at 15mins, everything sleeps at the appropriate time.
When on my desk, the drive is set not to spin down, and the MB to sleep never. Display at 10 mins I think. Again all works fine and very quietly - typically I can really only hear the drive at all when my ear is *right* beside the trackpad.
-Rob in the UK
PS: Data transfer from the old drive accomplished with the old dive in a USB2 enclosure, the new drive fitted in the machine, and the MB booted into 10.6 from the install DVD - used Disk Utility > Restore > Source > Destination. "

As I've mentioned before, I've also used the built-in Disk Utility "restore" (cloning OS X drives) feature for awhile now. (It's all or nothing basically unlike options with CCC or SuperDuper, but all I needed was a complete clone.)

"I put a WD 750GB Scorpio into a (unibody) 2.8GHz MacBook Pro 15" (MacBook Pro 5,3) running 10.6.1. Using it for 3 weeks w/o problems. It's thicker than the OEM Seagate it replaced, but fits perfectly. For all practical purposes it's silent, no problems with noise, it's all at about the same level of the system fan.
Drive clicking: definitely none.
Sleep settings: yes, it is set to sleep when possible, for both battery and power adapter.
(drive firmware) Revision: 01.01A.01 (looks like a first release)
Model: WDC WD7500KEVT-00A28T0

I don't benchmark my gear, but I'd say it's definitely slower than a 7200RPM drive. So overall, it's very smooth, cool and quiet. Just not a performance drive.
Best, Tom"

I think most buy these for capacity primarily (vs a 7200rpm 500GB drive). I'm using a 640GB/5400rpm/8MB cache notebook HD also (Toshiba 640GB, 9.5mm) in a 17in MBP w/10.6.2 and Bootcamp/Win 7 partitions. (No complaints with it so far.) I'd have chosen the WD 750GB instead but after taking one for the team on the 1TB Passport (usb only drive inside) last month (and damaging case taking it apart) I was lucky to get the 640GB in trade. (Taking a hit on price, but the USB only WD 1TB was worthless to me personally.)

" pix of drives (bare) at farm3.static.flickr.com/2501/4163968570_4e316edd27_b.jpg
Left to Right: 250GB Apple drive, 640GB & 750GB.

640GB (WD6400BEVT-00A0RT0, firmware 01.01A01) went into the Early 2008 MBP MB133LL/A w/ 4GB RAM
- Paid an Apple Authorized Service Providers $30 to install it so I do not void the extended warranty of the NVIDIA GeForce 8600M GT in case it fails (normally that shouldn't affect that. I've had to have PBs repaired that I had upgraded both HD and Optical drive - no problem getting warranty work done. The US has laws on warranty protection for consumers however and YMMV. Paolo replied to my comment on that.)
I saw your post and my fear of Apple Philippines or their local resellers has merit. The local shops are notorious with trying to dodge in-warranty service at the slightest provocation. When I had my uncle's white macbook case serviced for the known issue (discoloration & chipping lining) they gave me a run around for almost a month.

(regarding the 640GB WD in the early 2008 Mac Pro)
- I hear it click sometimes but it works like a charm (it was checked to sleep when possible)
(FYI - He later wrote however that since Snow Leopard (clean install then restoring some files from TM backup, he no longer saw the option to select 9400M vs 9600M GPUs in Energy Saver. I saw an apple forum thread (late 2008 and 2008 Macbook pro forum) where a few other owners saw this same problem. Interesting was some also commented on restoring some files via TM. One mentioned resetting SMC the 'old way' (as does with earlier user removable battery models) fixed his problem but I asked Paolo if he tried reapplying the 10.6.2 "Combo" updater. He later wrote he's also getting "service battery" messages now as well. I upgraded to SL over a 10.5.8 install on an early 09 MBP and have seen no problems like that (both GPUs selectable/shown in ASP, etc.). I've not done any battery run-down tests in SL however - some have seen much lower runtime in SL w/light loads (web browsing, etc) and one tip for that was running Safari in 32-bit mode (via Get Info option on app).)
- Had to use this drive (vs 750GB) because of the 9.5mm clearance (limit of 15in pre-Unibody MBP model. (All Unibody MB/MBPs can take 12.5mm high HDs, but only the 17in pre-unibody models can.)
- I noticed a speed up from the original 200GB Fujitsu Drive
- Planning to use it in a PS3 for a DIY hard drive upgrade
- Not available in the Philippines or Hong Kong. Had to buy it from the US.

750GB went into the Late 2008 MBP MB470LL/A w/ 4GB RAM
- Installed it myself and had to buy a larger handle #00 Philip screwdriver and a larger handle Torx Screw driver
- I don't hear clicking and it runs great
- Largest drive available for sale at the time of purchase
- I noticed a speed up from the original 250GB Hitachi Drive
- Planning to use it in a Xbox 360 for a DIY hard drive upgrade
- Not available in the Philippines or Hong Kong. Had to buy it from the US
-Paolo D."

(Added 2/23/2010 - updated again at 2/26/2010 4PM)
"13in Macbook Pro, 2.26Ghz, 4GB RAM, OS 10.6.2. Replaced 160GB stock apple drive with 2.5" WD 640GB Scorpio (WDC WD6400BEVT-22A0RT0) firmware 01.01A01.

Kona Speed test averages about 80MB/sec read and write on the 640GB. Compare this to the stock drive that benched at around 55-60MB/sec read and write.

Energy saver settings: Plugged in: Never sleep and no drive sleep.
Battery: Sleep after 10 min, put drives to sleep when possible.

So, I went for space over speed choosing this drive over the 7200RPM Seagate 500GB drive. I've had no issues in the past with WD's 5400RPM 2.5" 500 Blue which I have installed in 4-5 friends Macbook's and Macbook Pro's over the last year or so since they came out. I've also put 2 of the seagate 7200RPM 500GB (7200.4) laptop drives in co-workers Macbook Pro's also which have performed very well.

But I wanted space in my new 13", since it's my mess around laptop and not a "production" machine. Since the unibody Macbook Pro's can fit 12mm drives I would have ordered one of the 750GB or 1TB models (compared to the 9.5mm standard laptop drive) but I couldn't find them in stock from any reputable retailers. As honest as "Billy Bob's Computer Store" sounded, I'll stick to OWC or Newegg.

Anyway, I installed it, one pass zero'd the drive (old habit) and then installed a clean OS 10.6 off the install DVD's that came with the machine. This was done in a loud-ish room so I didn't notice any sound at all from the laptop besides the faint noise of the DVD drive accessing.

Ran software update over and over until nothing new popped up. Installed a few random add on's like Perian, Flip4Mac, iStat Menu's (which doesn't show network activity, I guess it's a known issue with version 2.0 build 200) etc. Repaired permissions then headed to bed to watch the USA-Canada olympic hockey game on the laptop. In my silent bedroom I start to notice the drive noises. The drive (remember, silent room) is WAY louder then the stock drive which even in a silent room was barely noticeable. Also it seemed like the drive kept trying to spin down then up then down up etc etc. Also as this was happening it would make that click noise (more like a "Clunk" then a click, if that makes sense) Sometimes the drive would spin all the way down and be silent for about 10 seconds, but it would soon spin right back up. Most of the time it would start to spin down but then spin up again. That dropping noise of the drive slowing down but then the motor kicking in to bring it back up to speed. Seems like a lot of wear and tear and battery drain. It was plugged in this whole time, and as mentioned above, energy setting set to never sleep, never spin down drive. Also I would see a little lag in safari as I was clicking and scrolling around that seemed to coincide with the spin down/up cycle on the drive. For the record sitting in a normal noise room I can't hear the drive, but in a silent room it is noticeable.
(General drive spinning or clicking noise? (I can hear my MBP w/5400rpm Toshiba 640GB HD in a very quiet room - almost sounds like low-level fan noise, but no clicking or stuttering issues seen with it.)
And he also later asked about Load Cycle counts - covered in an article here from Feb 2009 on Notebook HD Load Cycle Counts (from end users).)

So now I'm not sure what to do. I have a 2.5" firewire 800 case that I might put the drive in and see if it exhibits the same behavior (spin down/up) to isolate if it's a drive thing or a laptop thing. As nice as the space is (640GB) I might just buy the 7200.4 seagate 500GB drive which is blazing fast and not that much smaller (in capacity)....

Update (2/26/2010):
So I wound up using this: www.haque.net/software/hdapm.dmg which was off one of the sites linked here.
It solved all my clunking, and load/park cycle issue. Before it was rising at over 100 cycles an hour. (corrected number.) In 15 hours I had about 1,600 cycles. 100/hr. (The last WD 500GB Scorpio (blue) I owned (that seemed fine - quiet, no performance issues, etc. and no APM tweaks used) was reported as having just over 1 cycle every 2 minutes with my usage patterns. (It can vary depending on how much the drive is accessed of course - as well as APM/ES settings).)
Drive benched faster by a few MB after also. (that's likely within the run/run variation of most benchmarks (xbench especially))
I may have lost a few min of overall battery use from it, but my laptop is plugged in 90% of the time anyway.
Thanks again!
-Kevin"

I doubt that really matters much, considering the delta as a % of the laptop's total power use (cpu, display, motherboard, interfaces, etc.).

(Added 3/1/2010)
"I upgraded my Model 3,1 MacBook Pro (2.2GHz, 4GB RAM) with a Western Digital 640GB drive WDC WD6400BEVT-22A0RT0.
I made the swap about 6 weeks ago and I am very happy. It is virtually silent, runs cooler and quieter than the Hitachi 500GB drive it replaced and I recommend it to anyone looking to stretch their MacBook Pro to the max. I rate it a 10/10! You cannot beat it for the price.
(so you've noticed no clicking, etc. issues (not all owners have but some did.) But another factor can be the model it's used in (for example the many posts on HD issues from June 2009 MBP owners.))
No clicking at all. My iPod clicks, but the WD 640 is dead silent. Maybe it has to do with the version, that is why I put the entire identifier string from ASP. Maybe the version makes a difference. (your WD 640GB drive model is the same as the one a new 13in MBP owner used above) And it really is significantly cooler than the Hitachi it replaced.
(Just for the record I asked for the drive's firmware version (reported in ASP as the drive "revision")- as far as I know most all shipped as the same version currently though. 01.01A01)
The drive revision number is: 01.01A01
Best regards, Daevad"

I welcome other WD Scorpio (640GB or 750GB) owner feedback - let me know (via news at xlr8yourmac.com) your experience (performance, noise, any issues seen, etc.) and include your Mac model/series/OS and if you have Drive Sleep enabled or not in Energy Saver. If you've done any benchmarking that's also welcome. Thanks.
[BTW - after all the problem reports since the Mid-2009 MacBook Pros/EFI firmware update 1.7 was released (ref: a very long Apple forum thread on the subject (now removed), let me know if your MacBook Pro is that series/using that firmware update. Some posts in that thread mentioned replacing the SATA cable, forcing SATA I mode, etc. but none of those seems to have been a universal fix for everyone affected.]