If you have the same problem, you probably visited the discussion forum too here on Steam and might have seen the devs asking to post log files.

First, browse to the install directory of the game, since this is where the log files can be found (the script files we'll take a closer look at are located here too). The easiest way is to right-click on the game in the Steam Library page, and then choose "Manage >> Browse local files".

Next, locate the log file called "Logs/Sam4.log", and open it in the text editor of your choice.

If you look in this log file, you'll most likely see your GPU is indeed recognized. The lines we are looking for are similar to the example below:


So this means the game does indeed recognize the GPU, but for some reason will still claim it has no idea what GPU is installed.

Let's keep looking. A bit further down in the log file it will also say something like:


So even though the GPU is recognized, it seems the game is using a script file called "SystemCompatibility.lua". And for some reason, this script file fails to detect the GPU somehow.

Since this is a LUA script file, we should be able to easily check what is happening in it.

Open the file "Content/SeriousSam4/Config/SystemCompatibility.lua" with any text editor (notepad will do just fine), and near the end of the script we'll find the code that checks the GPU:


So it seems the script is able to detect the amount of VRAM on the GPU, but not the GPU specs.

The line dofile("Content/Shared/Config/PerfIndexGPU.lua") is of interest here, as it seems that is another script file that seems to be used to determine the actual GPU specs.

Since it's another LUA script file, we can simply open it in a text editor to see what it does.

In this file, we'll see that first a couple of variables are declared with information on hundreds of different GPU's, each with a performance index. A quick search through these variables quickly showed that my card (the 3080 TI) wasn't in the list, so it's probably safe to say that this is the actual problem. The game seems to use a hardcoded list of GPU identifiers, and if your card isn't in the list, you're out of luck.

If we look near the end of the file, this seems to be the case indeed:


If we take a closer look ath the "GetGpuSpecs()" function, we see that:

1. The function first determines the vendor based on the "sys_iGPUVendorID" variable: local gpuVendor = gpuVendorIDs[sys_iGPUVendorID]
   
2. Next, it uses this info to select the relevant variable with the list of GPU's for this vendor: local vendorGpuIDs = perVendorGpuIDs[gpuVendor]
   
3. Then it uses the list to find the actual GPU: local card = vendorGpuIDs[uwCurrentDevID]

If the last step fails, for example due to the hardcoded lists not having your GPU in them, then the script stops and returns the value "nil" (in other words: nothing) to the "SystemCompatibility.lua" script, which in turn throws the "GPUDetect" error.


Now that we know what the problem is, we can easily fix it. And there are 2 different ways to do this.

The first way is the easiest: we'll simply make the script believe we have a different GPU.

Open the "Content/Shared/Config/PerfIndexGPU.lua" script.

In the variables with the different vendors and GPU's, locate a card of similar performance to your own GPU. In my case, I used the info for the 3090, since the 3080 TI and 3090 are basically the same when it comes to performance in games.

Write down the identifier for this GPU. This is the value in between the square brackets in the line with the GPU info, for example "0x2204" in my case:


Next, scroll all the way down to the bottom of the script, and locate the following lines:


We simply need to add a new line between these 2 lines in which we manually set the "sys_iGPUVendorID" variable to the identifier of the GPU we chose earlier. The code should look like this:


Finally, simply save the changes to the file, and we're done. The game will now believe we have a different GPU.

The second fix is slightly more complicated, but a bit more elegant: we will simply add our own GPU to the existing list of known GPU's.

First, we need to find out what the device identifier is for our own GPU. We can find this in the log files we examined earlier.

The ID we are looking for can be found in the following lines in the logfile:


The identifier that we need can be found between the semicolon (";") and colon (":") of the detected device information, marked in bold in the line below:

#1: (10DE; 2208:38971462.00A1) NVIDIA GeForce RTX 3080 Ti (12108, 0/16296 MB)

So in my case, for a 3080 TI this would be "2208".


Next, open the "PerfIndexGPU.lua" script, and locate the variable with the GPU list of your own card's vendor (in my case, nVidia). In this list, locate the GPU that is closest in performance to your own:


Now simply copy the line of the GPU with the performance closest to your own GPU (in my case, the 3090), change the identifier to the one we found above (in my case "2208"), and (optionally) change the description to the name of your card.

And if you really want to, you could also update the performance value, although this is completely optional and won't make much of a difference.

The code should look like this now:



Finally, simply save the changes to the file, and we're done. The game will now recognize our GPU.

There you have it: we fixed the GPU detection!

The game will now start without the annoying message and without resetting your graphics settings each time.

And as an extra bonus, you'll also be able to use "Autodetect" to automatically determine the best settings for your system.


It's finally time to kick some serious butt!