This is really just a reference collection, since despite there being multitudes of threads containing all the steps you should really take when trouble starts, we get asked the same questions over and over again.
I realize that won't change, but rather than repeat posting those steps every time, on every thread, it's much easier and less time consuming, for us both, to simply provide the most common troubleshooting tests and a few really good links all in one place in order to eliminate unnecessarily long threads.
The first thing you should do, if this is a new build or you've just completed the installation of a new hardware component prior to the troubles starting, is read the very good sticky at the following link and triple check all the items listed there as more often than not the problem can be resolved by taking the time to perform each of those steps. If in doubt about any particular step, ask, or google it. There are often quite helpful images available here and at various other forums to assist with identifying whether or not something should look a particular way or is installed correctly.
Try the steps at the following two links, FIRST, if you haven't already:
*Perform these steps before asking about NO-POST issues
And if the problem is very likely to be hardware related, and you've just built the machine but have never had a successful post, or cannot post on a previously working machine, these steps outlined by Tradesman1 are a good way to find the issue:
*Bench testing to troubleshoot POST or no boot issues
If that doesn't help to resolve the issue, or it's NOT a POST related issue, then the following should be helpful in determining the issue. Not every problem will be found by performing every test below, but a good many of them will and at the very least you will have hopefully eliminated many of the potential issues to the point where more specific measures can be applied.
How to post images of hardware or test results in order to help with troubleshooting.
In order to help you, it's often necessary to SEE what's going on, in the event one of us can pick something out that seems out of place, or other indicators that just can't be communicated via a text only post. In these cases, posting an image of the HWinfo sensors or something else can be extremely helpful. Here's how:
*How to post images in Tom's hardware forums
Run HWinfo and look at system voltages and other sensor readings.
Monitoring temperatures, core speeds, voltages, clock ratios and other reported sensor data can often help to pick out an issue right off the bat. HWinfo is a good way to get that data and in my experience tends to be more accurate than some of the other utilities available. CPU-Z, GPU-Z and Core Temp all have their uses but HWinfo tends to have it all laid out in a more convenient fashion so you can usually see what one sensor is reporting while looking at another instead of having to flip through various tabs that have specific groupings.
After installation, run the utility and when asked, choose "sensors only". The other window options have some use but in most cases everything you need will be located in the sensors window. If you're taking screenshots to post for troubleshooting, it will most likely require taking three screenshots and scrolling down the sensors window between screenshots in order to capture them all.
For temperature monitoring only, I feel Core Temp is the most accurate and also offers a quick visual reference for core speed, load and CPU voltage:
*Download Core Temp
When it comes to temperature issues, taking care of the basics first might save everybody involved a lot of time and frustration. Check the CPU fan heatsink for dust accumulation and blow or clean out as necessary. Do not "vacuum" out your case or heatsinks as vacuuming is known to cause static electricity which can be damaging to components. Other areas that may benefit from a cleaning include fans, power supply internals, storage and optical drives, the motherboard surfaces and RAM. Keeping the inside of your rig clean is a high priority and should be done on a regular basis.
And CPU-Z offers a lot of information including memory configurations, RAM module part numbers, motherboard model number and revision information and some minimal GPU specs. They also offer "skinned" versions of the utility with ASUS ROG, Gigabyte G1 and OC and ASRock Formula versions.:
Test power supply with paperclip and multimeter
Checking system voltages by way of HWinfo or the BIOS is all fine and good, it will give you a fair general idea of what's going on with your PSU, but there are many cases when that's not possible or the issue needs a far more accurate accounting of the power to individual circuits. Sometimes, in cases when the system fails to even start for example, it's necessary to know if power is even being delivered to the motherboard or other components so you can narrow down the list of usual suspects. Here's two ways to test the PSU.
The first will tell you if it powers up at all, and the manual test which requires the use of an electrical testing meter, preferably a digital volt-ohm meter or DVOM will allow you to determine without doubt whether or not the PSU is providing the essential power requirements where it's needed.
Run Seatools for Windows or DOS
When a drive issue is suspected or the system won't boot at all, but does POST, you may need to test one or more attached drives. In order to do this, whether prior to booting into the Windows environment or once you've already booted Windows, you'll need a utility to perform the advanced testing necessary which is often not possible using the drives built in tests.
For systems that can't get into or install Windows, the Seatools for DOS utility will be helpful. You can generally create bootable media with this utility on CD, DVD or USB media. The Windows version can simply be downloaded and run from your desktop. For the Windows version I recommend running the Short drive self test and the Long generic test. There are also other tests available in the utility like the S.M.A.R.T test but the Short DST and Long generic will usually be all you need to determine most drive faults.
*Download Seatools for Windows
*Download Seatools for DOS
Pretty self explanatory here. Memtest is a memory module testing utility that is fairly accurate at finding and reporting errors that occur while the memory is under instructional stress. I recommend running it for the full 7 passes but modules with serious errors will usually throw errors fairly early, within the first few passes.
That's not always the case though, so test thoroughly and be sure to test each module individually, with only that module installed. That will allow you to know which module has issues and has the added benefit of not resulting in false errors, which often occurs when testing multiple modules simultaneously.
Once again, there are options for creating various types of bootable media, as Memtest needs to be run in a non-Windows environment.
Go to the Passmark software website and download the USB Memtest86 free version. You can do the optical disk version too if for some reason you cannot use a bootable USB flash drive.
Create bootable media using the downloaded Memtest86 (NOT Memtest86+, that is a different, older version and is outdated). Once you have done that, go into your BIOS and configure the system to boot to the USB drive that contains the Memtest86 USB media or the optical drive if using that option.
Click here to download Memtest86 USB package
Create a bootable USB Flash drive:
1. Download the Windows MemTest86 USB image.
2. Right click on the downloaded file and select the "Extract to Here" option. This places the USB image and imaging tool into the current folder.
3. Run the included imageUSB tool, it should already have the image file selected and you just need to choose which connected USB drive to turn into a bootable drive. Note that this will erase all data on the drive.
No memory should ever fail to pass Memtest86 when it is at the default configuration that the system sets it at when you start out or do a clear CMOS by removing the CMOS battery for five minutes.
Best method for testing memory is to first run four passes of Memtest86, all 11 tests, WITH the memory at the default configuration. This should be done BEFORE setting the memory to the XMP profile settings. The paid version has 13 tests but the free version only has tests 1-10 and test 13. So run full passes of all 11 tests. Be sure to download the latest version of Memtest86. Memtest86+ has not been updated in MANY years. It is NO-WISE as good as regular Memtest86 from Passmark software.
If there are ANY errors, at all, then the memory configuration is not stable. Bumping the DRAM voltage up slightly may resolve that OR you may need to make adjustments to the primary timings. There are very few secondary or tertiary timings that should be altered. I can tell you about those if you are trying to tighten your memory timings.
If you cannot pass Memtest86 with the memory at the XMP configuration settings then I would recommend restoring the memory to the default JEDEC SPD of 1333/2133mhz (Depending on your platform and memory type) with everything left on the auto/default configuration and running Memtest86 over again. If it completes the four full passes without error you can try again with the XMP settings but first try bumping the DRAM voltage up once again by whatever small increment the motherboard will allow you to increase it by. If it passes, great, move on to the Prime95 testing.
If it still fails, try once again bumping the voltage if you are still within the maximum allowable voltage for your memory type and test again. If it still fails, you are likely going to need more advanced help with configuring your primary timings and should return the memory to the default configuration until you can sort it out.
If the memory will not pass Memtest86 for four passes when it IS at the stock default non-XMP configuration, even after a minor bump in voltage, then there is likely something physically wrong with one or more of the memory modules and I'd recommend running Memtest on each individual module, separately, to determine which module is causing the issue. If you find a single module that is faulty you should contact the seller or the memory manufacturer and have them replace the memory as a SET. Memory comes matched for a reason as I made clear earlier and if you let them replace only one module rather than the entire set you are back to using unmatched memory which is an open door for problems with incompatible memory.
Be aware that you SHOULD run Memtest86 to test the memory at the default, non-XMP or custom profile settings BEFORE ever making any changes to the memory configuration so that you will know if the problem is a setting or is a physical problem with the memory.
System File Checker is a utility in Microsoft Windows that allows users to scan for and restore corruptions in Windows system files. Although the following link indicates Windows 8, SFC is compatible with all versions of Windows since Windows 98. The steps are the same for Windows versions prior to Windows 8.1.
*How to run SFC/Scannow
Check device manager for remarked devices
It's always possible for issues to be related to an individual hardware component or peripheral so checking for remarked (Device manager will generally show some kind of symbol, whether it's an exclamation or question mark) devices in Device manager located in Windows control panel. Don't confuse "Device manager" with "Printers and devices". They are two different applets/utilities.
If you open Control panel and change the view to large or small icons, you'll see the listing for Device manager. Once in Device manager, if there are remarked devices which will be indicated by the category being already open to the device listing and have a symbol next to the component in question. If no devices are remarked then there are not any fundamental issues with hardware devices such as hardware that simply isn't working correctly or in need of a driver update.
If there are remarked devices, you can use the following to help with solving those issues:
*How to use the Windows device manager for troubleshooting
*Microsoft article: Troubleshooting device driver issues with device manager
Run VRAM test utility and Furmark GPU stress test.
Both these utilities can be useful in diagnosing GPU related issues:
*Download Furmark GPU stress test utility
*Download CUDA GPU memtest utility
Check boot and OS partition structure
Checking partition structure, especially in cases where prior OS boot partitions may have existed on one drive or another can be resolved by managing the partitions using Disk management.
*How to manage drive partitions in Windows
Disconnect potential problem devices
Disconnecting devices like secondary or optical drives, changing connections to SATA headers, reseating cables or entirely removing the device from the system can also be helpful. On systems that have both aftermarket GPUs as well as integrated graphics, removing the PCI graphics card and using the iGPU from the motherboard or processor can be helpful to diagnose the issue by process of elimination. As with the bench testing methods listed above it's often helpful to just remove everything that's connected to the motherboard and power supply that isn't absolutely necessary in order for the machine to operate on a basic level. Plugging devices back in one at a time until the problem resurfaces may be the only way to isolate the issue in some cases.
Check driver versions
Sometimes the addition of new hardware can create conflicts or compatibility issues with existing hardware, or a particular driver that's already present may for whatever reason have been corrupted or compromised, possibly due to viral or malware infections, or in some cases it may be directly related to a minor corruption of the OS file system itself.
Other times it happens that a particular driver just doesn't want to work with your hardware device while a newer (Or in some cases, older) driver file works perfectly fine. It's rare that an OLDER driver will work better than a newer one, but it does occasionally happen. In any case, it's usually beneficial to confirm you're running the latest driver version which will likely have better functional operation and compatibility with a variety of hardware.
For graphics adapter drivers I recommend following the procedures outlined at the following link in the CLEAN driver installation section:
*The laymans simple guide to solving graphics card issues
For other types of drivers including those that support chipsets, USB ports, SATA storage controllers, PCI functions and other individual devices, it's always best to check the manufacturer's page for your motherboard or device as that's where the most current drivers with the best range of compatibility can be found the majority of the time. There are times when a better driver may be available elsewhere, for example, if the motherboard manufacturer hasn't updated the available drivers for some time but the hardware device manufacturer, Realtek for example, may have released a newer version that just hasn't found it's way onto the product page yet.
When the best drivers from the manufacturers product page, which is generally the recommended method, are not helpful or are incompatible you can also check for driver updates as outlined at the following link:
*How to update drivers in Windows
Run virus and malware scans
A plethora of issues can occur when a viral or malware infection is present. Both types of scanners should be used at all times to protect your system, as one doesn't usually provide the same capabilities as the other. Viruses and malware are nearly always mutually exclusive, employing much different methods to achieve the same goal, which is to confound you and mess things up in general.
The following link provides some solid advice for pursuing these types of issues and in addition you may also want to use a "second opinion" scanner like Hitman Pro which you can download for free from the second link. Rootkits are often undetected by either type of scanner, so if you know there is some kind of infection, but none of the other methods seems to detect anything, try scanning for rootkits as well.
*How to deal with Virus and Malware issues
*Download Hitman Pro second opinion scanner
*Download Malwarebytes free Rootkit scanner
Perform Windows repair or Reset, Refresh, Reinstall Windows OS.
When nothing else has helped, it may, unfortunately, be necessary to reinstall Windows and that can be done in a variety of ways so it's best to deal with that in a specifically case by case manner. Below are links for doing a CLEAN install of both Windows 7 and 8 though, just in case you already know that's the likely solution but have no idea how to go about doing so.
*How to perform a CLEAN install of Windows 7
*How to perform a CLEAN install of Windows 8 or 8.1
*How to perform a CLEAN install of Windows 10
If you still have issues, which isn't uncommon, after all of the above, I suggest you'll need further personal assistance which most any member of this forum will happily make every attempt to provide you with.