This is a base model with a single 3.5" drive cage to hold 4 drives which you NEED TO PURCHASE DRIVE CADDIES for as Lenovo sells them already attached to drives normally. There are plenty of 3rd parties on Amazon or eBay who sell them on their own to use with your own drives. The drive cage is connected with a mini-SAS to SATA break out cable that is connected directly to the motherboard. I had a spare LSI 9211-8i card that I popped in with a mini-SAS to min-SAS cable for now and plan to get the expansion kit from Lenovo that will include everything to add the second drive cage that will speed up the install when I do.

RAM is a bit on the light side, so consider getting more depending on the OS you plan to run and I wholly recommend sticking with ECC RAM if you plan to use this machine in any server like capacity.

The power supply is 450w and can be redundant when paired with another. Alternatively you can use a regular ATX power supply as the case has the screw mounts for it, but you will need an adapter to go from ATX to Lenovo's proprietary connector.

Consider this server if the Lenovo TS140 is a bit to restrictive for you.

1. For each hot swappable hard drive that you install, you will need to purchase a caddy. ($15 to $20/each) I love being able to add drives and swap them out without opening the case and consider the caddies well worth the cost. Just be sure that you have flat head screws to connect your drives to the caddies, because round head screws will not allow the caddies to be inserted into their slots.

2. The TS440 requires ECC memory, which is available from fewer vendors at a higher cost than non-ECC memory.

3. The TS440 does not come with an OS installed. I installed Windows 10 Pro with no problems.

4. The TS440's onboard graphics only supports a single monitor. I wanted dual monitors, so I installed an old Nvidia Geforce 9500 GT card, which is working fine after I downloaded and installed the drivers for it.

5. The TS440 does not support audio, so you will either need to install a sound card or get a USB sound device. I chose to install a $30 Asus Xonar DG card for $30.

6. If you decide to install a high end graphics card for gaming, then you will probably want to replace the 450 watt power supply with something larger. As other reviewers have mentioned, the PS cable to the motherboard is proprietary, so replacing it with a standard ATX PS requires an $8 adapter cable.

7. The TS440 does not include wireless of Bluetooth functionality, so if that is important to you, then you will need to buy cards or USB devices to support those features.

8. The TS440 does not include any hard drive. I installed a 250 GB Samsung SSD with a 10 yr. warranty for a little over $100, including the 2-1/2 in. to 3-1/2 in. adapter and caddy. I also added a couple of 1 TB drives. I elected not to install a RAID, which is an included option with the TS440.

Even with the potential add-on costs listed above, I am very happy that I elected to buy a TS440. The build quality is excellent and the performance so far has been great. I will be using the machine as an Adobe Creative Cloud workstation (Photoshop, Illustrator, etc.), for programming, and as a VirtualBox host. I probably could have bought a desktop PC just as capable of performing these functions, but with the TS440, I can add another hot swappable hard drive cage and four additional hard drives in the future.

Pros:
> Sturdy and well built.
> Very expandable.
> Fast enough for your needs
> Hot swappable hard drive bay.
> Hot swappable redundant power supplies. (comes with one though).

Cons:
> No hard drive caddies installed. you have to purchase them separately. Adds about $70 dollars to your cost.
> Really stingy with the internal ports. A small motherboard is used with a PCIe x 1 , a PCIe x 4 and a PCI slot. A larger board would have made more slots available.
> It's big. Bigger than I think it needs to be. But I didn't engineer the thing, so there's probably a reason for it.

Otherwise, I'm quite happy with the server and recommend it.