BIOS settings that may affect input lag:
All the settings in this section are for advanced users, if you are not sure what you are doing, better skip this section. Remember, everything you do - you do at your own risk! The author does not bear responsibility for the consequences.
The closest you can get this to 100.00, the better.
Memory strap (Memory Multiplier)
100:100. 100:100 should obviously provide better results since it matches BCLK. Memory with lower frequency and lower timing can reduce latency.
EIST, C-States etc.
Disable as many of these as possible because they bring a lot of lag cause of dynamically changing the cpu frequency.
Execute Disable Bit
Is an Intel hardware-based security feature that can help reduce system exposure to viruses and malicious code. I just disable it.
Intel Virtualization Technology
Disabled for any gaming PC if u dont use VirtualBox etc.
Probably 99% of people don't use it.
Enormous input lag. Should be disabled.
Disable unless you use it.
HPET (High Precision Event Timer)
HPET is a hardware timer used in personal computers. Disable to lower input lag and DPC latency (ASUS motherboards dont have this option).
Disable to lower DPC latency.
Hyperthreading (if u have i7):
For each processor core that is physically present, the operating system addresses two virtual (logical) cores and shares the workload between them when possible. Turning off hyper-threading gives more fps in csgo.
UEFI vs Legacy boot
Legacy tends to be better with a more classic mouse movement. PC will not boot if u have installed UEFI OS or have GPT filesystem.
CPU Power Phase Control
Extreme / Full.
CPU VRM Switching Frequency
Manually set 500Khz or higher.
PCIEx16_1 Link Speed
Manually setting Gen3 better than Auto.
Legacy USB Support
Usually have to leave this enabled in order to get back into the BIOS but sometimes will have better mouse response with it off. Varies highly by motherboard.
Other settings affect weakly or don't affect at all. There are some general recommendations:
Adjust in the BIOS - "off" everywhere is possible, disable unused SATA ports, monitoring case fans and stuff, but you need to remember, you are doing everything at your own risk!
Why is there so little?
There are many motherboard manufacturers, and there are plenty different chipsets, in the same time don't forget about AMD users with the same situation. Therefore, with all my will I can't cover the whole range of settings, but in time I will try to add. As it mentioned above, principle is simple - disable all unnecessary options, manufacturers features (like Asus Multicore Enhacement) and other. Do nothing if you are not sure, read first about specific option.
Everything written on is not for beginners. I can't write general manual for all systems, but I would love to do it. CS:GO positively responds to the increase in the processor's frequency, sometimes an increase for 400-600 MHz can give an increase of about 100 FPS and raise the minimum values, increasing the comfort of your game. The situation is such that having an Intel processor with an index K (4690k etc), it's enough to go into the BIOS, find the setting CPU Ratio there and set the desired value. The Cpu ratio is multiplied by the BCLK frequency, the Cpu ratio 45 multiplied by the BCLK 100 will give you 4500MHz, as a rule there is no need to change the other settings for this overclocking, most motherboards automatically increase the voltage to enough to work at that frequency, but if you know , what are you doing, you can set the value manually. Don't even think about overclocking with Intel box-cooler installed in your system, all this can be done if you have purchased a normal tower air cooler before :). After overclocking, monitor the temperatures with utilities such as RealTemp, AIDA64, MSI Afterburner and any others you wish to. Whatever you do, you do it on your own risk, remember this!