I have a Dell Optiplex 790 Minitower desktop computer. I am planning to upgrade to SSD.

Currently I have two 512GB Hard Disk Drive connected to my machine (via SATA0 and SATA1) and an Optical Drive (via SATA2).

I contacted Dell and asked whether I can upgrade to 256GB SSD or not, for which they said my machine supports maximum of 128GB SSD that they found through Dell manual (according to them) and also state that my machine has maximum SATA for 3Gbps (meaning it do not have SATA III). Later I searched for the Dell manual for my machine and found a Technical Guidebook where it is stated that I have one SATA III and 3 SATA II as shown below (Figure 1.0). But about the 128GB SSD, they were right. It is stated that my machine can support 128GB SSD and this is where I need help as 128GB SSD is not enough for me as I have to use some heavy application which requires a quite large storage (not for gaming).

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Figure 1.0: Page #14 from optiplex-790-tech-guide.pdf

Furthermore, I have seen some YouTube videos where they installed 256GB SSD on some other model of Optiplex 790 (click here).

To further investigate I used an application HWiNFO where it shows that my two existing HDDs are in port that provides 6Gbps but one of them is running at 3Gbps (which I wonder why?) as shown in the below picture (Figure 2.0). But the Dell Technical Manual I am talking about, I did not find anywhere mentioning the Gbps (Figure 3.0).

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Figure 2.0: HWiNFO result summary for my Optiplex 790 Minitower

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Figure 3.0: Page #04 from optiplex-790-tech-guide.pdf

Additionally, the below is the SATA ports on my machine's motherboard (Figure 4.0).

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Figure 4.0: Sata ports on Dell motherboard 0HY9JP.

To conclude, I want to use my existing two HDDs (500GB each) one will be connected to SATA1 and the other will be connected to either SATA2 or SATA3 (where optical drive is connected) and I want to install the new SSD on SATA0 (beccause probably it has the highest speed amongst all). Hence, can I install a 256GB SSD or 512GB SSD on my machine safely and will I get all the benefits of the SSD's speed (6Gbps) along with the two existing HDD (please note that I am okay if I have to disconnect/ sacrifice one HDD for safety and speed)?

Dell Documents:


After further research, I found here that Dell themselve is selling upto 1TB SSD for Optiplex 790 (Figure 5.0).

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Figure 5.0: Optiplex 790 Parts & Upgrades for SSD from Dell website

  • Your Dell computer supports any 2.5" or 3.5" SATA storage device. Since this machine due to it's age is unlikely to support UEFI then the boot device must be smaller than 2 TB in order to support MBR. Your machine will not support NVMe (even if you use a daughterboard) since those devices typically only support UEFI.
    – Ramhound
    Jul 24, 2020 at 10:07

1 Answer 1


Sure, your Dell computer shouldn't have a problem accepting any size of SATA-based SSD. (up to a reasonable amount) The 128GB number is more than likely nothing but what's officially supported by Dell themselves. After all, when the 790 came out all the way back in 2011, (affordable) consumer SATA SSD's only just hit this capacity.

The reason why one of your current drives runs at 3Gb/s is because, according to Dell's specs, your computer only has a single 6Gb/s SATA port. (SATA3) Why HWiNFO says 6GB/s @ 3Gb/s, no clue.

Make sure to connect the SSD to this port when you install it, otherwise you're just bottlenecking the drive. You can plug in your existing HDD's in the remaining ports and use them alongside each other.

  • 1
    The only reason Dell's documentation calls out 128 GB SSDs is due to the age of the documentation. It's only been recently in 2020 that larger consumer-grade SSDs with capacities that exceed 4 TB have appeared on the market. The different colored SATA sockets are due to the PC having two different SATA controllers. You also have a SATA 3 controller and a SATA 2 controller. You currently have one HDD that is clearly connect a 6 GB/sec to a single SATA III port.
    – Ramhound
    Jul 24, 2020 at 10:16
  • 1
    @MohammadZulfikar sounds about right!
    – MMM
    Jul 24, 2020 at 10:46
  • @Ramhound So you mean 'MMM' is right about that my black and blue ports, both are SATA 3 (6Gbps) right? Jul 24, 2020 at 10:51
  • 1
    @mohammadzulfikar I mean that your system will support up to 2tb SSD's and Crucial guarantee it if you purchase one of the drives in the link I posted. (But any 2tb SATA ssd will be OK)
    – davidgo
    Jul 24, 2020 at 11:03
  • 1
    @MohammadZulfikar - What I mean is that SATA is SATA. It's backward compatible, so a SATA III device will take a performance hit, if you use SATA II. The different color ports are to be used to identify which ports belong to what SATA controller as the end-user. Has nothing to do with the manufacturing process that's done by machine. Your screenshots clearly show you have SATA II ports and at least one SATA III port. You only have provided a screenshot with 2 SATA devices connected. Any 2 TB or less SATA SSD will work.
    – Ramhound
    Jul 24, 2020 at 11:37

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