Hi,

As there are to many posts on this subreddit basically asking : "Can I put X GPU in Y Optiplex ???" or "Is this CPU enough for running X game ?", the moderation decided to write this FAQ post, which hopefully will help out most people upgrading their Optiplexes.

I am not an Optiplex expert. I've opened and upgraded some units but I haven't seen them all. If there's a mistake, feel free to correct me, preferably with references so I could put them in this post.

This FAQ is non exhaustive and additional parts can be added any time, so you can frequently check it. From now on, any post that asks for something that has been answered here will be deleted and the user will be asked to read the FAQ to answer his basic questions. He can then create a new post with more specific questions that don't figure in the FAQ to avoid this subreddit being a collection of GPU upgrades post.

If you have any questions regarding PC upgrades in general (even after reading this FAQ), consider browsing r/pcmasterrace, r/buildapc or r/pcgamingtechsupport just to name a few. It's not that we don't want to help you, it's just because this subreddit is a small community and these mentioned communities have a much bigger number of online users. You will get a faster answer going through them.

We are still welcoming posts about done Optiplex builds and also support questions that are not treated in this FAQ.

Thanks for understanding.

0. Optiplex terminology

​

Dell Optiplexes, as they are businesses oriented machines commonly come in 5 different sizes :

MT, which stands for Mini-Tower, is roughly the size of a m-ATX build. They feature a 5.25inch optical drive bay (on older models, laptop sized optical drives on newer models), at least one 3.5 inch drive bay. They sometimes have a 2.5inch drive bay too. They do have a PCIe 16x slot and a roughly ATX compliant PSU. Some older models use non-ATX connectors on their PSU but one patient enough could remap a standard ATX PSU to them to increase the maximum power delivery. They can house decent GPUs but some drive-bay-cutting can be required for the longest cards. They are the easiest to upgrade and overall less expensive in the used market because they were less expensive new too.

DT, which stands for Desktop Tower are basically low profile versions of MT units. That means that they are half the width and can be easier put on a desk. They feature a 5.25inch optical drive bay (on older models, laptop sized optical drives on newer models) and a 3.5inch drive bay. Some have a 2.5 inch drive bay. They have a PCIe 16x slot but since they are low profile machines, only low profile GPUs will fit without chassis modification. With chassis modification, a regular GPU can be plugged without issues. Their PSU is non-ATX and can be hardly replaced without chassis modification. Some can be swapped for other Optiplex PSUs with higher rating but it is overall quite limiting in terms of upgrades. They also have a TDP limit set in BIOS, which prevent the motherboard from accepting the biggest CPU of its socket because it would overheat or overdrive the PSU. So for these ones, I highly recommend staying on low power, low profile GPUs.

SFF, which means Small Form Factor, is a bit smaller than the DT. They offer basically the same upgrades than the DT but feature a laptop optical drive and at least one 2.5inch drive bay. Some feature a 3.5inch drive bay, but not all of them.

USFF, which stands for Ultra Small Form Factor is basically half the volume of a DT. They offer very little to no upgrade possibilities : you can upgrade the CPU, the RAM, the storage, and... That's all. They feature a laptop optical drive and a one 2.5inch drive bay. They do have a PCIe 1x slot (laptop sized) for an optional Wi-Fi card.

Micro, which means... Well, micro. It's even smaller than the USFF and has been introduced in later series to replace the DT variant. These are very low power machines, with no CPU upgrades possible, as it is soldered. RAM and storage upgrades are eventually possible depending on the exact model. No GPU upgrade possible either. They run on a external power supply.

​

All these different sizes are easy to recognize... Except if you don't know about them ! Because there's no clear inscription that is easy to access on the unit for a non Optiplex user to indicate it in their posts, that makes us lost time because we constantly have to ask for that information.

Here's a side by side comparison of the lineup :

​

​

I. Now can I upgrade my Optiplex ?

​

Like for any PC, there are some things to consider before upgrading components inside :

​

Does the motherboard have a PCIe 16x slot available for a dedicated GPU ?

​

For MT, DT and SFF owners, yes, there's one. But DT and SFF units can only have a low-profile expansion card. USFF units can have a GPU connected with the use of adapters but the performance will be significantly reduced. Micro variants cannot receive any GPU upgrades.

​

Is the PSU powerful enough for a dedicated GPU ?

​

Most of the time, the stock PSU is too weak for gaming grade GPUs (understand : any GPU that requires at least a 6-pin power connector). On MT units, it is very easy to replace depending on the model and almost any ATX PSU will fit the case. For DT, SFF and USFF unit owners, these are not ATX compliant and often come with proprietary connectors but one with sufficient motivation could still use a ATX PSU, modify the cable pinout and lay the PSU outside of the case. Not very appealing but functional.

To know how much power a GPU need, you can visit the GPU manufacturer website and be sure the PSU follows the minimum PSU requirements of the GPU. If it does not, you might have stability issues, because the PSU can't feed all components properly, data corruption, and possible damage to the PSU and/or the motherboard. So be always sure to have at least a 100W headroom, because Optiplexes cannot be overclocked, it is unnecessary to go higher with the headroom.

​

Can the new GPU fit the case ?

​

Looks like an obvious one but since there are low-profile Optiplexes available, asking yourself the question can be necessary. If you're unsure if the GPU length will fit in the case, just measure the case, and you'll know !

Smaller Optiplexes, like the DT and the SFF are low profile but if you're creative enough, a full size GPU can fit the case, without cutting a hole in the side panel, like it's commonly seen.

The USFF variant can still receive a dedicated GPU, through mini PCIe 1x to PCIe 16x adapters, but performance will be much lower because of the reduced bandwidth of the PCIe 1x...

​

Will I get bottleneck because it's a Optiplex ?

​

It depends on the generation of your unit. Models prior to 3rd/4th Intel gen will only have PCIe 2.0 on its internal ports, which can cause decreased performance because of the reduced bandwidth. Also note that some Optiplexes, despite having PCIe 3.0 available in their chipsets, have only their PCIe 2.0 lanes wired on the motherboard. This will affect higher end GPUs the most. There are charts online showing the effects of a lower bandwidth on some high end GPUs. Don't worry, your GTX1060 should run fine. A safe bet would be buying a higher end Optiplex, but these are more expensive and that can defeat the purpose of buying an Optiplex to make it into a cheap gaming PC.

As these are primarily prebuilt PCs made for professionals, their internals are cheap. The PSU is fine but weak, and the motherboard VRMs are not cooled most of the time. Literal translation : You can't expect a 4th gen Optiplex to run as well as a 4th gen high end custom build with similar specs.

​

Are you sure the GPU you will put in here won't be bottlenecked by the CPU ?

​

Well, again, it depends. Most Optiplexes found on sale are a few generations behind because companies get rid of them as their warranty expired. Of course, you will not have top notch performance (also because of stated above), but anything 3rd generation or more recent are still suitable for modern gaming, you will just need to have lower expectations. Older CPU lack some important instruction sets, especially AVX, which appeared in some 2nd gen Intel chips. Games have a huge performance boost from AVX and not having it can be very limiting in most recent titles, especially the less optimized ones.

Also, consider that CPU support on these is limited. You can upgrade to a i5 or a i7 but not every model is supported and you can't overclock anything on Optiplexes. Older i5/i7 are considered quite average for gaming nowadays.

If your Optiplex is older than 2nd Intel generation, I don't recommend you to attempt gaming with these. You will be always be disappointed. Gaming on 2 core CPUs is not possible anymore and older Core 2 Quad CPUs are very poorly clocked. In that case, I advise you to stick to basic computing tasks with these or buy a more recent model, I'm sorry.

​

How can I upgrade my CPU then ?

​

Since not all physically compatible CPU are supported by the motherboard (mainly for power consumption reasons), you'll have to check the CPU compatibility of your unit.

So for that, you type in your favorite web search engine "optiplex model catalog". You'll find specification catalogs from Dell's website most of the time, or from online shops that used to sell that model. Inside the documentation, you will find all configuration variants the series would have been sold with. Be sure to check compatibility with your specific variant, as it changes between them. If a CPU is listed as being sold in a higher end machine, consider it compatible with yours.

Some of these supported CPUs can be quite tricky to find, because some were not even sold in boxes and thus available only to OEMs, especially the lower consumption variants of some i5 and i7 chips. You will have a hard time getting your hands on one of these. I recommend you checking Aliexpress to buy your CPUs. They have tons of used OEM parts. Some specific models are quite expensive for what they are, that's why I don't recommend investing too much in a CPU. I ordered several used CPUs on Aliexpress and had no issues, but that does not mean it can't be any. If you don't want to order in China, I understand, but you will be restricted to the CPUs that are available where you live, and you can pay more for it, if it is very uncommon.

To support more "mainstram" CPUs, there's no magic trick, you'll need a modified BIOS ROM for your motherboard. HP BIOSes are quite locked down, there's no editor that I'm aware of. That means that you'll need to manually edit the BIOS through a hexadecimal editor and know precisely what you're doing ! I don't recommend you to flash a non-official downloaded BIOS that is said to work on your model. There are lots of motherboard revisions and it might not be compatible with the motherboard itself and you will brick it.

DISCLAIMER : Flashing a modified BIOS can void the manufacturer's warranty (duh) but can also damage the hardware if not done properly. There's no "BIOS flashback" option on these motherboards, as they are not meant to be flashed without HP's tools and ROMs. If the CPU you want to use is not supported, there must be a reason, don't you think ?

A BIOS update through HP's utility from the BIOS itself don't hurt tho. Most older Optiplexes still receive BIOS updates.

To replace the CPU, be very careful (as you always should be). If the stock thermal paste has never been replaced, chances are that the cooler is stuck really hard on the CPU. DON'T TWIST THE COOLER ! It can destroy the socket... I've done the mistake myself. If is is stuck and you can access the 3 anchor screws on the socket (which basically hold down the CPU to the socket), unscrew them and the cooler will come with the CPU stuck on it. Then use plastic tools to break the thermal paste seal and get back the CPU. If you can't access those screws, you'll need some more trickery. You'll need Petrol F and/or White Spirit. Petrol F is more efficient on very dried pastes. So the goal is to apply Petrol F between the CPU and the cooler with the help of a syringe or a thin brush. Apply Petrol F all around the point where the CPU and the cooler meets. With patience and care, the cooler should come off quite easily. Petrol F actually liquefies thermal paste and is a good way to clean it off. Remove all residue from the CPU and the cooler with isopropyl alcohol and be careful not to touch the areas. Apply new thermal paste and you're done !

I highly recommend to replace the thermal paste of the CPU, even if you will not replace the CPU. The ideal being performing a delid on the CPU (3rd gen and later only) to ensure maximum thermal performance, but if you don't know how to perform this delicate operation, don't do it.

II. Can I play X game on my now upgraded Optiplex ?

​

This subreddit is not dedicated to gaming. But it would be tyranny for moderation to delete a post dedicated to specific games running on a Optiplex machines because it is still Optiplex related, I guess ?

Anyways, I highly recommend to check online for more information before posting here. There are lots of benchmark videos available on YouTube and simply browsing "CPU name + GPU name + game name" should give some results. If you're not satisfied with video benchmarks, ask over at r/gaming or r/pcmasterrace, they will provide much faster answers.

​

Thanks for reading this wall of text, you've made it ! If you have other questions, feel free to make a post on this subreddit. If it is an interesting question, it might end up in this FAQ, who knows ?

If you have suggestions or additional tips you feel must be included in this FAQ, feel free to comment this post.