Dell OptiPlex 790 USFF vs. Dell OptiPlex 990 USFF

Comparison and Differences

Dell_OptiPlex_790_USFF.jpg case front and back pannelDell_OptiPlex_990_USFF.jpg case front and back pannel
Model
Form factorUltra SmallUltra Small
CPU optionsIntel Gen2 i3/i5/i7; Celeron; Pentium;Intel Gen2 i3/i5/i7; Celeron; Pentium;
ChipsetQ65Q67
Dedicated GPU *N.A.N.A.
RAMDIMM DDR3-1333DIMM DDR3-1333
RAM slots22
RAM speed1333 MT/s1333 MT/s
RAM max8 GB8 GB
USB ports(7x)USB-A 2.0; (7x)USB-A 2.0;
Video portsDisplayPort 1.2; VGA;DisplayPort 1.2; VGA;
Other portsRJ45; Hdph; (2x) Mic; Line-Out; Line-In; PS2/COM; Serial; Parallel;RJ45; Hdph; (2x) Mic; Line-Out; Line-In; PS2/COM; Serial; Parallel;
Optional portsN.A.N.A.
SATA ports22
PCI slotsN.A.N.A.
M.2 slotsN.A.N.A.
Drive bays2.5in; 5.25in(slim);2.5in; 5.25in(slim);
PSU200 W200 W
Weight3.27 kg (7.20 lb)3.27 kg (7.20 lb)
Released20112011
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 790 USFF and Dell OptiPlex 990 USFF

Both computers, the Dell OptiPlex 790 USFF and the Dell OptiPlex 990 USFF, were released during the same year - 2011.

Both models have the same form factor, meaning reoughtly they have the same phiysical size and form.

Processor

The two models have the same generation of Intel processors. We think that the 2 generation of Intel Processors have enough power to execute all of the home and office tasks that most people will care to do.

Memory

Both models have have equal amount of ram slots (2 RAM). Usually two RAM slots are more than enough for most cases. However, the count should be taken into account when planning how much and what combination of RAM you are going to need for your system.

None of the desktops has an advantage when it comes to the speed of the RAM being used. Both models support RAM speeds of up to 1333. In addition, you will be able to install the same amount of RAM in both models, and most probably 8 GB of RAM will be enough for most people. However, if you will be needing more RAM, make sure to check other desktop models too.

Ports

Both models have the same amount of USB ports for total count of 7. If this is not enough, using a USB hub is always a viable option. 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 slots are located on the motherboard and it is where SSD, HDD and Optical Disk Drives are connected. Each of the two models being compared have 2 SATA slot(s). Keep in mind that having too few SATA slots might limit your options for connecting additional memory drives.

M.2 SSD interface allows you to transfer data with higher speeds compared to the old SATA interface. Unfortunately, neither the Dell OptiPlex 790 USFF, nor the Dell OptiPlex 990 USFF has one. However, you can still use a SATA SSD drive which should give you satisfactory performance.

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

Looking at the Power Supply Unit (PSU) of the two models we don't see any differences. For either of them you get a maximum power of 200 Watts. However be careful, many models have more than one power supply option. When buying your computer, it is a good idea to get a version with the most powerful PSU. This will potentially allow you to upgrade to a more powerful GPU for example.

Motherboard

Dell_OptiPlex_790_USFF_motherboard.jpg motherboard layoutDell_OptiPlex_990_USFF_motherboard.jpg motherboard layout