Question New CPU (s) don't work

[delijestefan]

Hi, this might be a long read but I genuinely have no idea what the problem is and I've searched 20+ hours trying to find a solution (not including the hours I spent trying to apply these solutions.

This was my system at the beginning;
CORE i3 530
r9 285 2gb
1tb HDD
ASUS P7H55-M
8GB(2x4) 1333mhz ram
CORSAIR VS450W PSU

To begin I wanted to upgrade my cpu to an i7 870 (Asus website says its compatible). So I bought one off eBay and upon installing it didn't work. This lead me to spending countless hours on why it doesn't work. What happens is I turn it on - all the fans come on, all the lights come on, no beep (s) and nothing boots.
This is everything summed up - I tried everything BIOS updates, more thermal paste, less thermal paste, got a second i7 870 sent to use (thought the original was broken), disconnecting everything that wasn't needed, running with cpu cooler, running without cpu cooler, jumping the mobo, CMOS reset - however it booted when I put the i3 530 back in every time. Side note - I broke a 4gb ram stick in the process so not happy about that.

So after searching I couldn't find 1 post or video where someone had a p7h55-m (not pro, le, lx etc) and used an i7 870 apart from one other guy who couldn't get it to work. So I got a new motherboard - p7h55-d (which came preinstalled with an i5 760) which had several people online with the same configuration so I thought it would work (both 870 and 760) - turns out it doesn't (I tried everything I mentioned previously). But now when I put the i3 530 back in the PC either is stuck on the ASUS splash screen or goes into BSD but I can fix that on my own if I get the i7 870 to work. All I want to know is why do both motherboards work with the i3 530 but not with the i7 870 and i5 760, even though the guy I bought off plus every other person online can make it work.

All cables are connected - the CPU connector, the ATX connector etc - trust me everything has been checked what feels like 1000 times now.


Thank you for reading.

 

[mdd1963]

your PSU might not have sufficient headroom for the CPU and GPU...see if you can get a display from integrated graphics with no GPU installed at all if that is an option with your MB...

Additionally, with a new CPU installed, you might need to remove power completely, and, clear/reset CMOS...(many mainboards' BIOS can be confused with new CPU swaps...) Either a momentary switch or jumper installed for a few seconds is used to accomplish this

 

[delijestefan]

your PSU might not have sufficient headroom for the CPU and GPU...see if you can get a display from integrated graphics with no GPU installed at all if that is an option with your MB...

Additionally, with a new CPU installed, you might need to remove power completely, and, clear/reset CMOS...(many mainboards' BIOS can be confused with new CPU swaps...) Either a momentary switch or jumper installed for a few seconds is used to accomplish this

Thanks for the reply. I forgot to mention I used an old 7750 (doesn't use 6 pin) and integrated GPU for all 3 cpu (s) and only the i3 530 booted up with all. I understand the power issue but why didn't it boot with the newer mobo I bought as it was preinstalled with the i5 760 meaning it worked beforehand.