I've just bought a new case that'll hold 20 HDDs, plus I'll be using a couple of SSDs.

I already have 7 4TB Seagate Barracudas. I plan to purchase another 13.

The CPU and motherboard is the  E3-1240 v3 and  E3C224D4I-14S.

I've not figured out the fan set up just yet on my case, but there will be anything from 7-12 case fans.

And the PSU I currently have is the Corsair TX650M.

 

One other question. How many drives can you safely connect to molex/sata power connector?

I bought a Lian Li D8000, and I also have 10 BP2SATA backplanes that I purchased.

For those that don't know, you can power them by using either a sata or molex power cable, you don't need to use both.

 

Cable management in mind, I was planning on getting two power splitters like this to try and keep the cables manageable. But that had me thinking that a single molex/sata connector would be power 10 drives each. Would this be safe? Would it make any difference at all.

My two largest servers use that PSU with 22 HDDs each, though they are all green/eco disks, if yours are all 7200rpm it may not be sufficient.

Do you means new case hold 20 HDDs was D8000 ?

As D8000 support dual PSU, you will use one instead two ?

 

For D8000 hold 20 HDD, I will install 2 PSU, the other one no need be Corsair TX650M, arrange 10 disks per PSU, in worse case a PSU burning the disks, it will burn 10 only.

As you found BP2SATA backplanes support molex/sata, that means you need 10 power plug total, if 2 PSU then each just need 5 plug, so you no need to buy any power splitters.

 

In fact, 650W ususally far enough for whole system, but you should take care about the 3.3v/5v combine power was 150w. This may get trouble for 20 HDD + other hardware. E3-1240 v3 haven't GPU, you need a display card.

 

I won't use those 1 to 5 splitters, 1 molex/sata for 5 disks was too weak and danger.

 

Buy a PSU ( make them power up in same time ), that's finish and easy job.

Edited April 11, 20179 yr by Benson

It looks like the ST4000DM000 HDD's that I already have are 5900RPM. So I currently have 7 of those.

I can find the ST4000DM005 (same model but newer?) for really cheap, £97. I believe that's the same, 5900RPM (it's actually difficult finding this information on Seagates websites, I'm having to use online shop listings so correct me if I'm wrong there).

 

The power ratings for the ST4000DM000 are:

 

 

And for the ST4000DM005:

Most important info is the spin up max current, e.g., my WD greens require 1.75A max on the 12v rail for spin-up, most 7200rpm disks require 2.5A, and adding that up with 20 disks makes a lot of difference.

Yeah, I noticed that the above information states 'average 12v typ amps' rather than maximum.

They are both 5900 RPM from what I can see though.

The TX650M has a +12V rating of 54amps. 

 

Think I'll be needing a new PSU then?

I tried looking in the PSU thread sticked on this page. But the recommendations on there seem a little outdated.

Could anyone recommend a 850w single rail PSU?

Hopefully planning to spend around £150 or less.

Just remember normal activity vs Parity Check/Drive Rebuild power consumption which has all drives up and spinning. 

This is a tool I found that seems fairly accurate and detailed, in regards to installed devices in the system. Should at least provide a bit of insight

 

http://outervision.com/power-supply-calculator

Most drives use fewer than 10 watts each, so 200W (that's under 20A on the +12V rail) total during normal operation for 20 HDDs. Spin-up is an exception where a drive can draw a higher amperage than at any other time.  So you could concern yourself with ensuring you have enough amperage on the 12V rail to accommodate 20 drives spinning up (40A, let's say) but even then your current power supply is plenty big.

 

I had 20 drives on a 450W power supply for years (it was a decent Seasonic model) and the only thing I noticed when I swapped it out for a 650W model was that my 20 HDDs reached full RPM a little quicker.

 

Your mileage may vary, but in my experience, PSU quality is much more important than its power rating.