Had a bluescreen ? Find out if it was due to hardware failure using the best all-in-one stability check & stress test available !

OCCT is the most popular all-in-one stability check & stress test tool available. OCCT is great at generating heavy loads on your components ( CPU, GPU, Memory, GPU Memory & Power supply ) , and aims at detecting hardware errors or stability issues faster than anything else. A monitoring engine is also embedded, to ease diagnostic and see how your computer reacts under heavy load using graphs.

Download Stable (X64)
6.2.2 Download (Latest Beta, X64)
7.0.0 beta 12

Trusted by many !

Special Notice

Issue with the latest AMD GPU Drivers and OCCT VRAM test

A workaround has been found and implemented in OCCT 6.2.2. Please update !

OCCT is free for personal use only !

If you are running OCCT in a corporate or commercial environment, you have to buy a PRO license to use OCCT

I see an increasing number of companies downloading the free version of OCCT and shamelessly using it in their corporate environment. The free version of OCCT is meant to make OCCT as useful and widely used as possible. This has been the case since it started, back in 2003.

This time, when you do this, you aren't stealing from a big company !

OCCT isn't enough to make a living as of now (far from it). Please support me and participate in keeping the free edition... free for everyone !

Features

Personal edition

5 Tests

OCCT includes 5 different tests : OCCT and Linpack for your CPU, 3D and Memtest for your Graphic card, and Power to stress your power supply. You can even monitor your PC while using an external app to generate reports using the Monitoring-only test !

Monitoring

OCCT will monitor your computer and present you real-time graphs showing you temperatures, voltages, fan speed, frequencies, component usage, and power consumption during your tests.

Built-in protection for your computer

Worried about frying your components ? Turn the maximum temperature threshold in OCCT's options ! Should a component reach this critical temperature during a test, OCCT will stop itself immediately.

Test report

At the end of a test, you will be able to save a full graphical report of what happened during the test, for diagnostic purposes. Free for the first 5 tests, with a personal license afterwards.

Pro edition

Allowed to run on domain-joined computers

OCCT's free edition won't run on computers joined to domain, this version removes that limit entirely

CSV readings export

OCCT will generate a CSV files containing all the monitoring readings upon saving a test report. Use it to build your own graphs !

Enterprise edition

Build your own test

Chain different test phases to build your own schedule. Everything is done graphically in the app, using drag&drop, for an easy configuration ! You can also export test configurations to a file

Detailed test report

Gain access to fully detailed, fine-grain test reports in HTML file format (single-file), allowing you to analyze easily the behaviour of your computer during the test, and use it as a comparison point between two different test runs.Preview it here !

Command-line support

Start OCCT with command-line switches, to automatically start a test, choose where to output the report, configure the report name,...

Pricing

Please be aware that all sales are final.

You can check our End-user License Agreement (EULA) here

Currency

Personal
(One Month)

$5.00

All Tests available
Embedded Monitoring
Overheat protection
No waiting time
Test Reports

Personal
(1-Year)

$25.00

All Tests available
Embedded Monitoring
Overheat protection
No waiting time
Test Reports

Pro
(1 year)

$150.00

All Tests available
Embedded Monitoring
Overheat protection
No waiting time
Test Reports
No Windows domain lock
CSV readings export

Enterprise
(1 year)

$499.00

All Tests available
Embedded Monitoring
Overheat protection
No waiting time
Test Reports
No Windows domain lock
CSV readings export
Chain tests
HTML reports
Command-line support

Help us translate OCCT !

Translating OCCT is easy. First, download the english translation file : English.lang . Save it next to OCCT.exe and rename it to the language you're going to translate OCCT to.

Edit it using your favorite text editor ( i like Notepad++, but any will work - make sure you keep UTF-8 as the encoding though).

The first line says : <Language Name="English"> . Replace "English", obviously.

You'll then find the block for the language codes supported by this translation. Just list whichever language code applies to your translation. These are used by OCCT to automatically load your language file on startup, by matching this code with Windows's display language. For instance, here is the French language code list :

You'll find a list of language codes here. Look at the last column.

Then, it is just a matter of replacing every string by its translation. When you're done, start OCCT, and your translation will be available in the option menu (the gear icon). Test it, and send it to support@ocbase.com

Faq

Which test is the best at detecting hardware errors ?

CPU:OCCT, Large data set, with Auto number of threads is, hands-down, what will detect CPU/Memory/Motherboard stability issues faster. Use GPU:3D in fullscreen mode for GPU testing, GPU:Memtest for testing your Graphic card's Memory, and Power supply for testing your PSU. Most errors are detected within the first 5 minutes. However, i recommend doing at least a 1 hour long test just to be sure.

Which test puts the most stress on the CPU ?

If you have an Intel CPU, try the latest Linpack version available. OCCT's CPU Test with Small data set is the best on AMD CPUs, and a close second on Intel CPUs.

GPU:3D and furry donut based tests are Power virus

NO ! A Power virus is a stress test that you do not have control upon. This term was applied to OCCT's GPU test when we launched its first version, 10 years ago, by the marketing team of a certain brand of graphic card's manufacturer, when their shiny new graphic card could not withstand the test at all - it blackscreened instantly and required a reboot. This was due to a design failure of their reference design board. I don't know why the term stuck, despite being wrong. GPU:3D is a stability test just like the others.

Starting at how many errors do you consider a computer unstable ?

Seriously : One.

The Memtest says "crashed" right after starting ?

This may happen when there's not enough contiguous memory available for the test - use a lower value to get around this ! ( this is scheduled to be fixed with a more meaningful error message very soon)

Why isn't GPU Memtest's allocating all the memory on my card ?

A part of the memory of your Graphic card is allocated by the OS (for rendering the desktop and such), and other applications. The test goes to the maximum allowed memory allocation on your graphic card - until OpenCL spits out an error in fact. This usually ends up being more than 90% of your graphic card's total memory, depending on your graphic card model and your current usage, mostly.

Do I have to purchase OCCT to know where the errors come from ?

No ! The Free version has always been designed to be usable "as is". OCCT isn't withholding information from you (I would call that stealing). It detects errors, but can't tell you where they come from. On the software point of view, it is as if it asked the for 2 + 2 and got 5 as an answer.

It is because the CPU miscalculated and answered that 2 + 2 = 5 ?
Is it because the memory stored a 3 instead of a 2 ?
Is it because when transferring the 2 from the memory to the CPU, the 2 got transformed to a 3 ?

As there's no sure way of reproducing the error that occurred, there's no way of knowing what is going on. To further pinpoint errors, you have to dig yourself : lower the CPU frequency a notch and see if things are going better, up a voltage very carefully and see if it holds better... and pinpoint where the errors comes from. If you have access to spare parts, it is even easier to diagnose : replace and see what's going on.

I lost my license : how can I get it back ?

Send an email to support@ocbase.com and please give us at least a day for sending you your license back.

I am not using OCCT in a commercial or professional environment, yet my computer is joined to a windows domain. Can i run OCCT ?

Only the PRO version of OCCT will accept to launch on a computer joined to a windows domain. This is meant at detecting uses in professional and commercial environment, as they heavily rely on Windows domain. In the past, as there are enthousiasts that have a Windows domain at home, we offered a way of disabling this check as they were indeed not in a commercial environment, but this saw too much abuse. About 90% of the requests were from people trying to avoid the PRO license entirely. We thus removed that possibility, and you indeed need a PRO license now to run OCCT on a computer joined to a Windows domain.

Changelog

Version 7.0.0.b12

MONITORING : Added usage graphs for Intel iGPUs (Thanks Сергей & Mew ! )
MONITORING : Fixed lots of issues regarding the graph resizing (Thanks Сергей ! )
MONITORING : Settings now save the last displayed tab in monitoring (both testing and monitoring area)
TESTING : Fixed a bug where without license the test would sometimes revert from infinite to 30min instead of 1 hour

Version 7.0.0.b11

SETTINGS : Added flags to control the monitoring - Enable and disable them at will in case of issues !

Version 7.0.0.b10

SYSINFO : Switched to a tab view
MONITORING : Fixed an issue where when the memory was under heavy usage, graph refresh could freeze (tentative fix) - Thanks Madoka !

Version 7.0.0.b09

MONITORING : fixed an issue where the tables where not resizing properly
MONITORING : Saving the current sensors and restoring them should work fine now
SYSINFO : Fixed AVX/AVX2/AVX512 detection (was broken since previous beta)
POWER : the test works again
MAIN : more code cleanups

Version 7.0.0.b08

SYSINFO : Revamped the whole screen - CHECK IT OUT :) It's pretty impressive now.
MONITORING : Saved the selected current sensors and stuff
REPORT : Added current chart
REPORT : Modified the report size and reorganized it again
UI : Change button order and wording
MAIN : code cleanups and numerous bugfixes

Version 7.0.0.b07

MONITORING : Fixed system usage report not updating sometimes
MONITORING : Added "Current" sensor category
MONITORING : Added "Other" sensor category (without graph, obviously) (That's a lot of info, be warned)
MONITORING : Fixed some sensors assigned to the wrong category (especially in the Fan category) (Thanks SynE !)
VRAM : added slider, similar to Memory test, for selecting the amount of memory to test
UI : Minor wording corrections (Thanks MustangIsBoss ! )

Version 7.0.0.b06

MONITORING : Revamped the system usage report in the testing area - now supports several GPU, and with clickable buttons
MONITORING : Fixed sensors not saving ( Voltage, Fan ) and showing weird behavior
MONITORING : Added support for Memory usage and GPU Usage for AMD GPUs
3D : Enabled tests to be run on displays without any display attached
REPORT : Fixed a lot of stuff in this report, and simplified it
UI : Minor binding bugfixes

Version 7.0.0.b05

MONITORING : Fixed enabled sensor issue ( Thanks David !)
MONITORING : Fixed sensors that were sometimes disabled when running the memory test (delay was too short) (Thanks David)
REPORT : fixed an exception when saving the report (still has to see some work to be done - it's missing the GPU Memory graph) (Thanks David)
UI : Fixed some buggy icons

Version 7.0.0.b04

MONITORING : Added Asus EC support
MONITORING : Added DIMM temperature (and more) support

Version 7.0.0.b03

MONITORING : Fixed system usage not updating (Thanks Tyllo !)
MONITORING : Fixed (part of) the translation in the SysInfo tab (the rest will get translated just right before release) (Thanks Tyllo !)

Version 7.0.0.b02

SYSINFO : the amount of memory available is now properly detected (Thanks Aeryn !)
MONITORING : Graph's vertical axis should now display the proper unit (Thanks Austin & David !)
MONITORING : Enabling/Disabling sensors won't throw exceptions when doing so on graphs that were never displayed (Thanks David !)

Version 7.0.0.b01

MAIN : Switched to HwInfo as my monitoring engine
UI : OCCT's UI is now split in 3 areas : Stability (for testing, the old view), SysInfo for system information, and Monitoring for a full view on monitoring
UI : this moves forced me to remove the expander (as it does not apply to every UI component)
MONITORING : rewrote like 70% of the code for better value handling, better graphs,...
MONITORING : adding a tab for sensors regarding the computer's "Usage"
MONITORING : added "GPU memory" to the list of usage graphs in the stability testing area of OCCT
TESTING : OCCT now tracks and reports WHEA errors that occurs during tests

Version 6.2.2

VRAM : Found a workaround with the AMD drivers past 20.4.2 - test is now working again on those !
3D : fixed a bug in multi-gpu environment where the first card was always used

Version 6.2.1

UI : Minor graphical fixes
TRANSLATIONS : Updated

Version 6.2.0

MAIN : Switched to a JSON setting file instead of the default .net framework - this makes for no reset of the settings when updating OCCT, and a more portable version
MAIN : fixed a rare race condition where updating the graphs could crash the UI - very rare though ( Thanks Justin !)
MEMTEST : Added a new system memory test ! Pattern-based for now, it strives at finding errors quicker than anything else. Try it out ! (Thanks Tyllo and all the nice people from the JEDEC Fan club Discord server ! )
CPU:OCCT (& MEMTEST) : Added an option for 20 & 48 threads in the dropdown
CPU:OCCT : renamed Instruction set from No AVX to SSE
LINPACK & 3D : Fixed a few control alignments in the test configuration (Thanks Сергей)
3D & POWER SUPPLY : Fixed a bug where the test would default on the GPU with a display attached
POWER SUPPLY : Fixed the "Auto" instruction set reverting to the highest level of AVX available when switching tests sometimes
GPU:MEMTEST : fixed references to VC++ redist ( those DLL are no longer needed)
SETTINGS : OCCT now ties its enabled sensor configuration to the Motherboard Name. If it changes, OCCT will revert to the default enabled sensors.
SETTINGS : The folder where Screenshots and Reports are saved is now part of the settings file (Thanks Сергей)
SETTINGS : Added an option in the settings window to turn off the Auto-Updater

Older versions

Version 6.1.1

MAIN : Adjusted the slider betweek graph/table views in the monitoring section when using small screen resolution (Thanks James )
MAIN : The error count will now reset faster when restarting a test (Thanks Austin)
GPU MEMTEST : The error count won't reset to zero after reaching 2 million+ errors (Thanks Clément)
TRANSLATION : updated Romanian, georgian, and minor fixes

Version 6.1.0

CPU:OCCT : Updated the Thread count tooltip to better reflect what the test is actually doing
3D : Completly rewrote the 3d test : no longer displays a window (this is normal !), and much more efficient than before
3D : Added a Limiter slider to lower the load on the selected GPU
3D : removed FPS limit, Resolution, and Fullscreen option (no use anymore)
POWER : Fixed the instruction set icon in the summary sometimes displaying "No AVX" when the test is using AVX
ENTERPRISE : Added a json file showing the result of the test at the end
ENTERPRISE : fixed 3d test icons reverting to the default (cogs)
ENTERPRISE : fixed a bug where the CSV file were not generated

Version 6.0.0

MAIN : Revamped a lot of parts of OCCT that had technical debt
MAIN : LOTS of bugfixes everywhere
MAIN : rewrote the test scheduler of OCCT to pave the way for future updates
MAIN : revamped a lot of parts of OCCT that had technical debt
MAIN : Increased the area available for test names in the UI
MAIN : Better handling of multi-GPU and various bugfixes
UI : Revamped the test UI for selecting Infinite/Timed tests
UI : Dropped the "Timed with idle periods" test in OCCT - it is replaced by the "monitoring-only" test
UI : got rid of the space in the test thumbnails - fits much better in tight spaces !
TEST : added a monitoring-only test that will do nothing, but once cancelled/finished, enabling you to generate reports
3D & POWER SUPPLY : Fixed a bug where the resolution list could be empty on startup
REPORT : Names are now prefixed with OCCT- for better sorting
TRANSLATIONS : Added Uzbek (Thanks Sher Khan !)

Version 5.5.7

GPU:MEMTEST : The test will now run on graphic cards without any screen attached, or when used remotely ( 3d test requires a screen)
TRANSLATION : Updated Portugues (Brazilian) ! (Thanks Francisco !)

Version 5.5.6

MAIN : Fixed a bug where the time displayed resets to 0 if a test runs for more than 24h
SYSINFO : The max TDP won't appear as "-1" anymore if it could not be detected

Version 5.5.5

TRANSLATION : Fixed a bug where changing the language might empty Dropdowns in CPU:OCCT (Thanks Siegmour)
TRANSLATION : Fixed a bug where the column names weren't properly updated when changing the language (Thanks Siegmour again !)
TRANSLATION : Added support for Spanish (Argentina) (Thanks Oswy !)
TRANSLATION : Updated Portugues (Portugual)

Version 5.5.4

3D : Fixed : errors detected in the 3d test were not always reported in the main UI (they were still shown in the 3d window)

Version 5.5.3

TRANSLATION : Added support for Turkish (Thanks Levent)

Version 5.5.2

MAIN : Overheat protection wasn't working anymore - it is now !
MAIN : Moved to a more standard "HH:MM:SS" display of time (in reports, in the UI...)
MAIN : The UI correctly recalculates the table minimum size in fullscreen mode
SYSINFO : The CPU Usage chart won't flicker anymore
SYSINFO : The current amount of installed memory is now being displayed ( translations of the title are going to be done later on )
SETTINGS : Settings are now saved when starting a test (in case a crash occurs)
TRANSLATION : Added support for Portuguese (Portugal) in addition to Portuguese (Brazilian) (Thanks Luis !)
TRANSLATION : Added support for Indonesian (Thanks Pag !)
TRANSLATION : Added support for Bulgarian (Thanks Boyan !)

Version 5.5.1

MAIN : Fix Graphic card detection in Windows 8

Version 5.5.0

MAIN : Several bugfixes in UI
MONITORING : Engine update (supports more hardware)
MONITORING : Rewrote the monitoring part of OCCT from scratch (might not seem like it, it's a complete overhaul, a prerequisite for upcoming stuff)
MONITORING : added a red spacer to resize graph/table to your heart's content
SYSINFO : introduced system specs as a tab on the right-hand side of OCCT
TEST REPORT : Several bugfixes - the system specs will be incorporated soon
TRANSLATIONS : Added Croatian (Thanks Maric !)
TRANSLATIONS : Added Hungarian (Thanks Efemel !)
TRANSLATIONS : Added Slovak (Thanks Jozef ! )
UI : Added link to our website in the About section
GPU3D & GPU:MEMTEST : Telling graphic cards with the same name apart is easier (they will have an ID next to their name)
GPU3D : Test can now properly select the selected graphic card in case they're the same model with SLI disabled
GPUMEMTEST : Test can now properly select the selected graphic card in case they're the same model with SLI disabled

Version 5.4.2

MAIN : Updated Authenticode signature ( SHA-1 and SHA-256 )
TRANSLATION : Updated Simplified chinese and Danish (Thanks !)

Version 5.4.1

MAIN : Added authenticode signature - When app has enough reputation, smartscreen warnings should go away !

Version 5.4.0

GPU:Memtest : First release ! An new OpenCL test that uses the same algorithm than memtest86 to test your GPU memory
UI : Reworked CPU, GPU and Power supply icons
UI : Fixed a display-issue only where OCCT displayed a license expired when it was still valid in the about window
TRANSLATION : Updated a lot of language files

Version 5.3.5

CPU:LINPACK : Fixed a bug where false positive could be reported in some (thankfully rare) cases
Translations : Updated Korean language (Thanks again JaeHyung)

Version 5.3.4

POWER SUPPLY : Fixed a bug where the selected instruction set wasn't properly saved
Translations : Fixed Korean language not appearing
Translations : Updated several translations

Version 5.3.3

CPU:OCCT : Added instruction set to test summary in the UI
CPU:LINPACK : Fixed a critical bug with Linpack parsing on CPUs with a huge number of cores - false positives were reported in some (thankfully rare) cases (Thanks Stephen !)
CPU:LINPACK : Improved test efficiency on CPU with lots of cores
CPU:LINPACK : Removed the ability to specify memory in percent, as between 1GB and 8GB is best
GPU:3D : No longer slows down when its window gets out of focus (Thanks SSateneth)
GPU:3D : Improved graphic card selection in multi-GPU configurations
GPU:3D : Fixed a crash when GPU:3D has more than 30 sensors to display
POWER SUPPLY : Switched to CPU:OCCT in small data set instead of Linpack
MONITORING : The max temperature threshold can now be disabled/enabled with a checkbox and is disabled by default
TESTING : Added a difference between "Cancelled" (triggers when a user closes GPU:3D's window for instance ) and "Crashed" (the test process terminated unexpectedly)
Translations : Added Danish (Thanks to Martin !)
Translations : Added Korean (Thanks to Jaehyung !)

Version 5.3.2

CPU:LINPACK : Fixed a critical bug with Linpack parsing on CPUs with a huge number of cores - false positives were reported in some (thankfully rare) cases (Thanks Stephen !)

Version 5.3.1

MONITORING : Huge update to the monitoring engine - better readings, newer CPU support
MONITORING : Updated how the default sensors are picked. New algorithm avoids selecting sensors with readings above max threshold for temperatures !
CPU:OCCT : Auto mode now disables AVX by default on AMD CPU in all data set sizes
MAIN : increased the waiting screen width to fit most translation in one line for looks
Translations : Added Japanese (Big thanks to Masao !)
Translations : Added Chinese (Simplified) (Thanks QMRQ ! )
Translations : Added Chinese (Traditional) (Thanks Danfong ! )
Translations : Added Swedish (Thanks Nilas ! )

Version 5.3.0

UI : Main window is now fully resizable
MONITORING : added Min/Max value columns in table view
MAIN : Improved license and .lang file detection speed
MAIN : Fixed a bug with some .net framework that are missing a particular registry function
MAIN : Fixed an issue where OCCT could crash at startup when no graphic card driver was installed
MAIN : Fixed a display bug with test durations over 24 hours
Translations : Fixed a bug where putting a corrupt English.lang file next to OCCT.exe could crash the app

Version 5.2.1

CPU:OCCT : fixed an issue where small data set might trigger an exception on some Ryzen CPUs

Version 5.2.0

CPU:OCCT : Huge update to the test
CPU:OCCT : Small data set is much more efficient and surpasses even Linpack
CPU:OCCT : Better support for high number of cores
CPU:OCCT : Much better AVX2 and AVX512 support
CPU:OCCT : User can select which AVX instruction set is used
CPU:OCCT : Updated CPU:OCCT's Auto rule for instruction sets to disable AVX in small data set for AMD CPUs
Translations : Added Dutch translation (Thanks Menno !)
Translations : Fixed an error where the included translation file in OCCT would take precedence over the one in a .lang file

Version 5.1.1

Generates simple crash reports when the main UI encounters an unexpected condition

Version 5.1.0

CPU:LINPACK : Better handling of "use logical cores" and simpler startup
CPU:LINPACK : Test is now more optimized optimized, Check it out !
GPU:3D DX11 : Test has undergone a huge update in this version
GPU:3D DX11 : Higher load on the GPU
GPU:3D DX11: FPS limit now works again
GPU:3D DX11 : added back sensor display
GPU:3D DX11 : Fixed mouse cursor displaying in fullscreen mode
GPU:3D DX11 : removed dependencies to old DLLs
GPU:3D DX11 : Fixed error detection algorithm on some Quadro GPU
GPU:3D DX11 : Fixed a rare bug where GPU:3D could fail to start
GPU:3D DX9 : Removed
UI : Fixed a few typos
UI : Number input checking much improved
UI : Fixed a bug where duration > 24 hours where not fully displayed in remaining time during a test
UI : Fixed a crash when right-clicking the title bar. Silly me.
UI : While OCCT is running, computer sleep (both screen and system) should be prevented
Translations : Removed unused strings and update to language files
Added Czech translation (Thanks Jaromir !)
Added German translation (Thanks Jürg !)
Added Italiano translation (Thanks Dendari ! )
Added Polski translation (Thanks Jaroslaw ! )
Added Romanian translation (Thanks Doruletz !)
Added Ukrainian translation (Thanks Arefiev !)
BIG THANKS TO PHOBOS !

Version 5.0.1

Fixed an issue with CPU:OCCT small data set not performing as expected
Fixed an issue with CPU:OCCT not counting the cores properly in auto mode
Fixed a display issue with the number of cores used in CPU:LINPACK (it was a display issue only)
Fixed the overheating detection taking into account all sensor, not only enabled ones
Fixed the "Test progress" sentence not translating
Added Spanish language (Thanks German !)
Added Slovenian language (Thanks Jadran !)
Added Portugues language (Thanks Maxence and his girlfriend !)
Updated Russian language (Thanks Konorimci !)

Version 5.0.0

Complete UI rewrite ( material design )
Updated all tests to count the number of errors instead of stopping at the first one
Updated monitoring engine
Updated Linpack with a 2019 version
Reimplemented most things
Features are too numerous to be listed here - it is a complete reboot of the program