I got really frustrated trying to find any sort of support help on ASUS’s Swedish website. It’s worthless. I still have the same issue though and I really appreciate your continuous updates on it Tobi in hope of finding a solution.
So here is my next update 
After talking to asus for hours they dont have any idea to help us…
So i infestigate a few more tests and i find an solution (hope that will work for more the 24 hours )
I uninstalled all asus and intel driver (this you only have to do if you have they installed 
) and then i go to the asus website and downloaded the chipset driver only and installed it. And now after a reboot its pcie x16 
I the maen while i installed all the other asus/intel driver and software and at the moment its fine
Maybe it hold on and i wish you that this will you help too
Good Luck
Ok so, I managed to find what my issue was. The top x16 PCIE slot is broken and will only link my gpu as x1, no matter how many times I reseat my card. I put the gpu into the x8 slot and now it all works as it should (for being x8).
In the beginning me and Tobi thought it was software relaterd (such as drivers or bios issues). So I started with trying to update all chipset drivers and try different ones. I then tried updating bios.
In the beginning I was not able to update my bios at all. In ASUS’s own EZ Flash 2 software inside the bios it always said “Selected file is not a proper BIOS file” when trying to load my BIOS file from a FAT32 formatted USB drive.
I later on managed to update the bios via ASUS’s flashback function. If you do use this function make sure you rename the BIOS file according to what your motherboard manual instruct you to.
I pressed in the flashback button for about 3 seconds and then the button started to flash in varying speeds. In the end it quit blinking and the bios was updated.
After that moment I was able to flash the newer bios using ASUS BIOS based EZ Flash 2 software.
itsTobistar3’s issue was not hardware based while mine was.
Now running my gpu in the x8 slot works way better. I notice significant difference in performance in Forza Horizon 4.
My results running the built in FH4 benchmark on ultra settings (running my gpu in PCIE x1) = 46fps achieved
My results running the built in FH4 benchmark on ultra settings (running my gpu in PCIE x8) = 108fps achieved
My 3DMark Firestrike score also went up with about 3500ish in GPU score and I currently get ~29500 instead of 26000.
Thanks everyone in this thread coming up with ideas for me to try.
I would also like to specifically thank @CodenameJack447 for a lot of back to back troubleshooting in the thread and especially @itsTobistar3 for helping me with troubleshooting my PC for the last couple of days.
Is nice to know you fixed your issue. Congratz! However, sorry about your broken pci slot: as you can see, pass from 1x to 8x doubled your framerrate, while somepeople think there’s no difference between 8x and 16x, i noticed the 8x bus bottleneck gpus at 4k 120hz (3 monitors in nvsurround portrait). The thing is i upgraded from 4790k with asrock z87 extreme 9/ac (plx chip) to 8700k with asus maximus core. And i had to deliver both cpu and motherboard because the sli 8x/8x show worse fps than 16x/16x provided by my 4790k (this is because the bandwidth needed for 4k surpass the 8x bandwidth, in fact i guess when 8k 120hz was available we will need something bigger than pci express 3.0, maybe 4.0 or 5.0). So i finally purchased 7700k + z270 supercarrier because of plx chip, ddr4 and cpu oc to 5ghz. At 1440p in this game i can maintain fixed 120fps with only one card, while in other games i can reach 120fps at 4k. z370 doesn’t have any plx motherboard actually, but the z390 ws pro will be the only motherboard to support sli 16x/16x. So people should be able to look into this motherboard if they want a good sli scale with a 9900k.
I guess my next purchase will be a 9800x with the z399 ws sage. My purpose is do 3-way sli with 1080ti + 40lane cpu + 2xPLX chips that would allow 16x16x16x16x. Of course not because of this game, but other dx11 that could benefit of it.
If you still wanted to change your motherboard there’s and asus x99 motherboard with plx chip that would increase your pci to max in case you wanted to sli at 16x16 even with a 28-lane cpu.
Plx chipset motherboards are not popular since the regular webpages like tweaktown, techpowerup, gamernexus, etc… Never test these motherboards with SLI.
Glad to have helped you.
I just bought a 1080 ti and it performs worse than my old 1070 here are my specs
And when I first booted up the game it ran at between 120 and 140 fps at 5760x1080 with my old video setting for my 1070 then randomly dropped to roughly 30 and doesn’t really go higher
Ryzen 7 2700 4ghz
Corsair h150i
Aorus x370 gaming 5
16gb ddr4 3000 mhz cl 16
Evga 850 g3
Msi gtx 1080 ti gaming x
hey everyone can someone plz help me im frustrated i have noticed my pc isn’t as good as it should be in comparison with the benchmarks on the internet , i get like 20 fps in FH4 what could be the problem ? cpu - motherboard - gpu ??
my spec :
ASUS STRIX X99 GAMING
Intel® Core™ i7-5820K CPU @ 3.30GHz
NVIDIA GeForce GTX 1060 6GB
16gb of RAM