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Extreme OC AMD APU

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Benching Team Leader Super Moderator
Dec 19, 2012

Over the last week I have trying to get a 7870K AMD APU to behave. Maybe I should have waited before I hit it with LN2 but I didn't. I thought maybe the cold would help since I was pushing it pretty hard. Turns out that was the problem after all. My water loop at home runs at approx-15c give or take and the the CPU would get almost to the end of a 3DMark 03 run and quit during the nature scene. Being a longer bench mark I assumed that it was getting too hot and just locking up. I was getting the same behavior in Heaven extreme and also in Catzilla 720. So I prepped the board and went to work under the pot. I already knew that the 7870K had issues with the cold but was supposed to be good to at least -50c. So I struggled along for 6 hours Saturday. Upping this voltage lowering that one. Changing ram stick timings, NB speed and GFX speeds all to the same ends. It was literally driving me up the wall. I was about ready to chuck the whole thing against the wall when I thought lets see what happens when I let it get a bit warmer. At -10 on the pot I finally finished a run of 3D03. OK then maybe I'm onto something. Seems the harder I pushed the iGPU the warmer it needed to be ??? Weird I know but in the end I ran it with the pot at ~20c and BIOS temp of ~30c and finally managed to get the runs i needed for the DIV V competition.







Now this APU behaved a lot better. Ran full pot a -180c It did OK and I have to wonder if I'm missing something. I do know I was just plain tired Sunday after benching till 2AM the night before and it's evident in my ram settings. Someone forgot to move the speed back up after going for another hail mary run at top speed so my points may have suffered a bit. I still managed to get 2nd in both SPi even with the crappy timings. I still think something was holding me back from top speed. I get to 6.5 no issue but anything over that regardless of core/nb voltage would crash instantly. I later thought that I should have dropped the GFX core speed but too late now. I just wanted to get some benches in before I ran out of juice so I was a bit sloppy. But here are a few pics just for fun.






http://hwbot.org/submission/3143257_ For some reason I can't get this image to work?

A couple of cold pics.


Full pot boiling under load at 1.9v

full pot boil.JPG

And one I just like to call THE FOG. This is the 6700K I believe

the fog.JPG


Benching Team Leader
Jan 2, 2005
5000/6000 APU series were somehow stronger. 6000 is probably the last one for higher memory clocks too. I had no issues with A8-6600K on ss/dice except that I killed first mobo in 2h but I guess it was some hardware weakness. Probably BIOS chip died and there was only single chip with disabled recovery.

At the end you made some nice results :thup:

Dr. McCoy

Feb 19, 2010
I've noted the newer model APUs tend to be cold bugged, my 7870K certainly is.
Also tried my 860K and it's the same, bugs out once it starts getting cold.

Good job on the comp Johan, ATM I'm not worried about these comps since I have more important concerns going on here.
I may one day jump in but for now..... Nah.


Senior Member
May 3, 2004
Awesome man! Great stuff!

The amd apus are a heckuvalotta fun to bench! Glad you got them figured out. Man...and congrats on taking the top slot!!!


Benching Team Leader Super Moderator
Dec 19, 2012
Well round II is here and I'm running out of time. It's been a couple busy months for me and some personal matters have been taking up a lot of my time. I'm back in the saddle again and been spending some "quality" time with this 7870K again. I'm starting to think now that the CB may not be as bad as I thought initially and might have more to do with my setting in BIOS than the temps. I do know this CPU can't get "too" cold that's a known issue with these but I'm going to try again this weekend to give it some cold and I'm fairly confident I should be able to run some negative numbers on the pot with it. Last time I was so frustrated with it, didn't even seem to run properly on my cold loop. So I started over again from the ground up working the GPU clocks up and have managed to get a 200MHz increase on the iGPU this is on 3DVantage haven't tried Heaven or Catzilla with it since they're not the benches for this competition round. After a couple back and forth subs, I'm sitting in first with a fairly comfortable ~500 pt lead for this benchmark. I know it doesn't seem like a lot but with top scores in the 12000 range it's a big jump for #2 to get me. I'm still ~600 pts. behind hwbot's high score for the R7 iGPU hopefully I can fix that on Friday.


3dvan 12728.JPG


I've also picked up another APU. This one for some high speed 2D benching. The 6800K doesn't have the CB that it's newer relative does and should run full pot, hopefully in the mid 7 GHz range. It also seems like the prime candidate for 3DMark 2001 just have to be able to run it at 6.5GHz + Seems like a decent chip so far bench 01 at 5.2 with good voltage so I'm hopeful that I can bag the second round by the time the weekend is over.

01 54695.JPG