Dell OptiPlex 990 MT vs. HP ProDesk 400 G6 SFF

Comparison and Differences

Dell_OptiPlex_990_MT.jpg case front and back pannelHP_ProDesk_400_G6_SFF.jpg case front and back pannel
Model
Form factorMini TowerSmall
CPU optionsIntel Gen2 i3/i5/i7; Celeron; Pentium;Intel Gen8&9 i3/i5/i7; Celeron; Pentium;
ChipsetQ67B360
Dedicated GPU *GeForce GTX 1650GeForce GT 1030 Low Profile
RAMDIMM DDR3-1333DIMM DDR4-2666
RAM slots42
RAM speed1333 MT/s2666 MT/s
RAM max16 GB64 GB
USB ports(10x)USB-A 2.0; (4x)USB-A 3.0; (4x)USB-A 2.0;
Video portsDisplayPort 1.2; VGA;DisplayPort; VGA;
Other portsRJ45; Hdph; (2x) Mic; Line-Out; Line-In; PS2/COM; Serial; RJ45; Headset; Line-In; Line-Out;
Optional portsParallelSD card reader; Serial; Serial and (2x) PS2; DP/HDMI/VGA/USB-C;
SATA ports42
PCI slotsPCIe 2.0 x16; PCIe 2.0 x4; PCIe 2.0 x1;PCIe 3.0 x16; PCIe 3.0 x1 ;
M.2 slotsN.A.M.2 2280/2230 M-key (PCIe x4); M.2 2230 (WiFi/BT)
Drive bays(2x) 3.5in; (2x) 2.5in; (2x) 5.25in;(2x) 2.5/3.5in; 5.25in (slim);
PSU265 W180 W
Weight8.87 kg (19.55 lb)4.6 kg (10.14 lb)
Released20112019
Manuallinklink
Price**Check PriceCheck Price

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* Dedicated GPU warning: Check if your particular power supply model has enough power. Additionally some PSUs don't come with an auxiliary PCIe power connector and you may need to buy a SATA to PCIe power adapter.

Differences between Dell OptiPlex 990 MT and HP ProDesk 400 G6 SFF

If you are looking for a more modern desktop, then you should go with the HP ProDesk 400 G6 SFF which was released in 2019. The Dell OptiPlex 990 MT is older and entered production in 2011.

If you are looking for the smaller form factor the HP ProDesk 400 G6 SFF is the right one for you. It is smaller than the Dell OptiPlex 990 MT and will fit more easily under your desk.

Processor

Usually the newer the generation of the CPU, the better the performance and efficiency is. If your budget allows it, you should go with the HP ProDesk 400 G6 SFF as it is running a newer generation CPU. This is not to say that Dell OptiPlex 990 MT is bad - it can still run some powerful CPUs, albeit being an older generation.

Memory

The Dell OptiPlex 990 MT has 4 RAM slots while the HP ProDesk 400 G6 SFF has only 2 slot(s). This is not something to worry about. Just make sure you take it into consideration when planning how much RAM you are going to use.

The HP ProDesk 400 G6 SFF is using the faster 2666 MT/s RAM. The Dell OptiPlex 990 MT is slower by supporting RAM speeds of up to 1333 MT/s. Additionally, if you will be needing a lot of RAM, better go for the HP ProDesk 400 G6 SFF as it has the ability to run 64 GB of RAM. The Dell OptiPlex 990 MT can do a bit less at max 16 GB. Most of the times, this should be sufficient for the majority of users.

Ports

In total the Dell OptiPlex 990 MT has 10 USB ports. The HP ProDesk 400 G6 SFF is inferior in this regard and packs 8 USB ports. In any case, if you miss USB ports, you can always purchase a USB hub. None of the desktop models has a USB 3.1 port (10Gb/s), so if you need a fast connection to your peripherals, like external Solid State Drive, you will need to look elsewhere.

The DisplayPort is usually the more popular video port used with desktops and laptops, while the HDMI is used predominantly in consumer electronics. That's why, it is good to see that both of the models come with a DisplayPort.

None of the models has an HDMI port. If your monitor supports only the HDMI interface, you will need to buy an adapter. Such adapters are cheap so nothing to worry about.

SATA ports are placed on the system board and it is where you connect your HDD, SSD and Optical Disk Drives. More SATA slots will allow you to have more drives running at the same time. In this regard the Dell OptiPlex 990 MT is better equipped as it comes with 4 SATA slot(s), while the HP ProDesk 400 G6 SFF has 2 slot(s).

If you want the fastest transfer speeds for your SSD, an M.2 interface is crucial. Thus, if the M.2 SSD slot is a mandatory requirement for you, go with the HP ProDesk 400 G6 SFF. Sadly, the Dell OptiPlex 990 MT has no such slot, and you will be forced to use the SATA interface instead.

Make sure that the available M.2 slot supports the PCIe (also called NVMe) interface. This is important as there are M.2 slots which support only the inferior SATA III interface. For comparison, the SATA III interface has max speeds of 6Gb/s, while the PCIe 3.0 x4 will support speeds up to 32Gb/s!

Power Supply

Having a Power Supply Unit with high power rating is important, if you are going to use components which require extra power. The HP ProDesk 400 G6 SFF comes with a decent 180 Watt PSU, but the Dell OptiPlex 990 MT has a more powerful one rated at 265 Watts. Choosing either one depends on your specific requirements and use case. Also don't forget that some models might have more than one PSU option - try to always get the most powerful one, especially if you plan to upgrade to a powerful GPU.

Motherboard

Dell_OptiPlex_990_MT_motherboard.jpg motherboard layoutHP_ProDesk_400_G6_SFF_motherboard.jpg motherboard layout