m17x R3 Hard Drive near GPU failed

This seems to be a similar problem to one that has been posted earlier but further down the line. My drive has now failed. I was using HDD sentinel to keep an eye on things for weak sectors, temperature and also SMART info. Temps were higher than the other drive but never above 60. Yesterday it developed 8 bad/weak sectors.HDD sentinel recommended remapping those on the physical rather than logical drive but it would be a destructive fix. I chose to use the chkdsk option to mark the bad sectors and left for work.

By the time I'm home - registry file blue screen error and can't reboot. It looks like it's rapidly developed another issue. I do have crashplan for backup purposes so can get stuff back after I fix this.

I have had my laptop which is about 5-6 years old now with the original 750gb drives in default RAID 0 configuration. I was thinking in recent months about upgrading to an ssd for the primary and a large capacity hard drive. The only upgrade I'd done on this as per MickyD's sage advice was the 680m as two 580s had failed.

I left things too late I guess and now my hand is forced. So my tentative plan is this - get a Samsung 850 Pro 1tb as the boot drive (I wanted the pro for more comfort of warranty, failure etc). Still thinking about the EVO though too.

Also as a replacement for the drive near the GPU - a large capacity drive.

My questions are this - with the R3 is there any limit on HDD capacity? I'm aware the maximum height is 9.5mm so no getting any 3TB drives or better as they are all as far as I know 15mm. With the 850 being 7mm (I think) then I believe I have to get an adapter to 9.5 so that it doesn't hang loose.

Does anyone know what the maximum capacity for a 9.5mm hard drive is? Ultimately though, it being near the GPU I'd want a robust hard drive rather than capacity so would settle for less but not lower than 1tb and preferably 2tb.