I just wonder about several error messages, indicating installation problems with the CH340 driver. I've tried several sources, including GitHub, and now I think that the available drivers are 32 bit only? Or is Windows supported only up to Win7, as an INF file suggests?
Can anybody help with error messages like "Driver Pre-install failure!" in DriverSetup(X64), or installation of this driver in general?
I'm running the 'official' driver from the Chinese site on Win7 and Win8. Both 64 bit.
http://www.wch.cn/download/CH341SER_ZIP.html.
I only ran the setup.exe so maybe I have the 32bit driver installed (?).
That version also shows above error on my system.
The Github link shows the driver supports both 32 and 64 bit .
I’ve used with no problems on a win 7 machine
Same problem there 
I never got any ch340 running on Win 7 Ultimate. 32 bits drivers don't work and 64 is not available. More over CH340 is not able to distinguish between board A or B. Easy for load ups but not easy if you want to connect with a specific board. If you want to work with CH340 on Windows you need a 32 bits system.
Alternative, buy boards that has an Atmel of FTDI chip for UART.
My chip may have been defective. On Win7 the driver install failed, on Win8 the driver installed but could not establish a connection.
Mine is win 7 ultimate 64 bit . I just installed it and it worked fine , also ok on my 64 bit laptop .
What error are you getting ?
Janhgm:
Alternative, buy boards that has an Atmel of FTDI chip for UART.
That is not impossible - the CH340G serial adapters you get on ebay for $1 each, while they usually work, are... still $1 serial adapters (and the ones you get elsewhere for more are typically the same ones, just with a higher price). The build quality is often shoddy - I have seen ones where the USB connector wasn't completely soldered on.
I normally use the black ones with the voltage switch (the black ones that don't have the voltage switch are trash - they don't break out DTR, and are the ones where I saw the USB connector not soldered down properly), or the green ones with the micro USB connector and voltage switch. The green ones are probably my favorite (a bit harder to find, but they are there on ebay), since everyone has buckets of micro usb cables, while full sized usb extension cables are somewhat uncommon. The term i search ebay for to find CH340G adapters is "ch340g 6pin" (without the quotes). And yes, this being direct-from-china-ebay-land, your best bet to identify what you're buying is the pictures.