first please forgive me for my bad english.

I have my secondary desktop from 2014 (HP pro 3500mt g2) and it has w 8.1 with bing. my hdd broke down and i replaced it with ssd. i don't know how to install windows 8.1 on it though.

Windows 8.1 is a SFF/tablet/emerging market SKU, which could only be the reason why it was installed on that HP. As an example, in the US, that OS would not be allowed to be put on that hardware, as can be seen in the specs which primarily shows Windows 7.

https://support.hp.com/us-en/document/c03364089

If you had purchased this PC new from HP and it came with this OS, then you would need to get the recovery media from HP. Otherwise, you'd need to get a new license for an OS, Windows 8.1 or otherwise for reinstall.

Because Windows 8.1 with Bing is not a retail edition, the installation media is not made available to the public.

3 hours ago, Tripredacus said:

Windows 8.1 is a SFF/tablet/emerging market SKU, which could only be the reason why it was installed on that HP. As an example, in the US, that OS would not be allowed to be put on that hardware, as can be seen in the specs which primarily shows Windows 7.

https://support.hp.com/us-en/document/c03364089

If you had purchased this PC new from HP and it came with this OS, then you would need to get the recovery media from HP. Otherwise, you'd need to get a new license for an OS, Windows 8.1 or otherwise for reinstall.

Because Windows 8.1 with Bing is not a retail edition, the installation media is not made available to the public.

But this is not completely my pc. mine is the g2 variant of this one. i got confused too but on this model there is no pentium g2030 that my pc has. So there is absolutely no way of me reinstalling w 8.1 on this? w10 activates automatically thanks to the key being on the motherboard, but w 8.1 home does not  

5 hours ago, BluePanda98 said:

But this is not completely my pc. mine is the g2 variant of this one. i got confused too but on this model there is no pentium g2030 that my pc has. So there is absolutely no way of me reinstalling w 8.1 on this? w10 activates automatically thanks to the key being on the motherboard, but w 8.1 home does not  

I'm assuming you also tried installing and activating the Pro edition of 8.1? You cannot activate a Home edition of Windows with a Pro key, and vice versa.

Assuming that doesn't work, and assuming you have the drivers for the laptop already, use NirSoft's ProduKey to find the OEM key that's installed on the motherboard. If an 8.1 key is not there, you'll have to purchase another key I'm afraid.

Edited December 18, 20205 yr by AeroSeeker

Hp sent me original iso for my desktop pc. Thank you guys for your help.