Phenom II 720 some problems with stability

Hello together.

My Phenom II 720 is running at 3600 mhz (18x200) with a Northbridge frequenqy of 2400. That's the limit I've found for the Cpu (at 1.5 Vcore).
It is stable for 7hours of prime 95 small ffts (maybe even longer but I stopped after).

While overclocking I had my ram "underclocked" to 800 mhz. It's stock frequency would be ddr3-1333.

I've increased the Ram speed again and the system lost stability (only 10 min prime 95 blend test).

The strange thing is that when the processor runs at stock speed (but still 2400 nb) it is stable so the ram shouldn't be the problem right?

What should I do to make my system stable at ddr3-1333 (even ddr3-1066 isn't stable when overclocked)? I've even increased Ram voltage by 0.2V but it wouldn't help.

Another problem that I have is that the Motherboard (Gigagyte ga-ma790fxt-ud5p) doesn't allow me to increase the v-core by more then 0.6 V but I need to increase it to 1.5 so that I wont need Amd overdrive anymore. Anyone knows a solution for that problem?

My ram:

Psu: corsait tx 650

Cpu cooler: xigmatek hdt-s 1283

I was already utterly disapointed that the Cpu wouldn't overclock further then 3600 herz I even needed to Use Acc(0,0,+2 to even get 3600 stable but now even this overclock starts to make truble.

PLEASE help me. The System I've built is the project for my final school "paper", I have to get good results.

Kind regards Erdinger

Ps: if you need anymore information don't hesitate to ask
28 answers Last reply
More about phenom problems stability
  1. Did you unlock the 4th core with ACC? That can cause instability in some cases. I would also explore running the ram @800 and seeing if you can tighten the timings there...the gains you get might be greater than the faster speed. I think if you turned off ACC you can get the speed back up, but it might be at the expense of the 4th core or better cpu overclock. Keep in mind chips are like snowflakes, no two will overclock the same.
  2. No you understood me wrong. The 4th core just wouldn't run no matter what I did the system couldn't boot.

    But I have the newest Bios version and you don't only need to allow Acc to enable the 4th core, you also have to load Ec firmware "hybrid" which i don't.

    I only use Acc to stabelize the system. I've read somewhere that if you've got a weak core putting Acc at 0 for all other cores and at +2 for the weak core can lead to higher overclocks and that's what I experienced.

    Without this Acc tweak I couldn't get above 3.5 ghz and 2200 nb but after it a 2400 Nb is stable and I can reach 3.6 ghz.

    So again the 4th core is NOT running.

    Still thank you for you're time.
  3. Alright, I just wasn't sure since you mentioned the ACC but nothing about the 4th core. I know a lot of people by that board and chip combo just hoping to unlock the 4th core. I would still try to explore leaving the memory at the lower speed and tightening the timings. It might not look as impressive on paper, but it should get you better benchmarks.
  4. I've read an article here on toms where ddr3-1333 at 7-7-7-20 was one of the best perfoming solution. ddr3-1066 was also ok but ddr3-800 performed badly. Maybe only 4 fps less in games but still... I have baught ddr3-1333 rated ram and I want it running at that speed..

    Another thing I just saw is that Cpu-Z sais that they run in single channel mode... Befor I had the ram placed in slot 2 and 4 now I tried it at slot 1,3 still cpu-z says Channels: single

    What the hell is wrong here?
  5. your channels should be color coded. Is it reading all the ram? It is possible you have bad ram or a bad memory controller on your cpu or on the dimms.
  6. Here is the article I think you were referring to if you want to double check the data and the advantages of each.,2319-8.html
  7. it reads all the 4 gigs. slot 1,2 white 3.4 blue.. I had it in 1+3 and 2+4
  8. you need to have it in 1 and 2
  9. K i'll try that... Any idea how I can increase the Voltage in bios to 1.5V? (max setting is +0.6)
  10. I'm not familiar with your board and bios...maybe one of the AMD guys can chime in here and help you with that. I'm not even sure what the voltage limits are on those, so I wouldn't want to tell you something that fries your processor.
  11. K I already have the processor running at 1.5 volt in Amd overdrive but my stupid Bios has a insane low Voltage limit..

    Your advice on the ram however was excellent they're now running in dual channel.

    I always thought i had to use the different colours (it also was like this in my old rig i think)

    Still the other two questions are a pain in my A££.

    I have to give this Pc away for some time so that the teachers can rate my project .... It would suck to have to tell them to use overdrive..
  12. can't you save the settings to have it boot to that profile w/overdrive? I think now that your ram is seated correctly you will have more luck getting it to the correct speeds. On modern boards each channel is marked in the same color.
  13. i Think you can't save the settings in overdrive because the programm is only made for "testing" the settings before putting them into the bios, so that you don't need to reboot everytime and so that a to high setting doesn't need a cmos reset. If it saved to settings it would risk to "destroy an Os because it would always crash after booting.

    Also its a software on which I depend(and which uses resources) I would just love to have the options in my bios so that I could change os or give the pc away without having problems.

    I'm building this system for a school project. It's just unproffesional with Overdrive.

    The system is still not stable when doing blend test if the cpu is overclocked--> error core 2 if not it is stable so it should be a cpu problem but the cpu ran stable for 7 hours small fft.

    It doesn't make sense.... I need the help of some people with experience in amd systems but somehow nobody reads the thread.(expect you of course, thanks again for the help at least the ram runs dual channel now :))

    Maybe there are some voltages I could change to get the ram stable. I tried upping the Nb but it didn't really help. The problem is that I don't think it's the Ram which is unstable because at stock cpu speeds it isn't. But the Cpu "should" also be stable because it passed 7hours small ffts.

    Maybe it's the Cpu Nb i need to work on. I don't know
  14. Ok I think I solved the problem with the ram. I figured the only connection between Cpu stability and Ram stability is the Cpu Nb. It was stable at small ffts but wasn't stressed as much as with the blend test after...

    I increased the Cpu Nb voltage by 0.5 more and now it is stable. (atleast for 15 min blend test ^^ more then ever before at ddr3-1333)

    Still a mistery though why this instability only shows when I Increase Cpu frequency an Cpu nb speed, but not if only Cpu nb speed is increased and cpu frequency at stock. (only multiplier overclocking so the Cpu nb doesn't change)
  15. erdinger said:
    K I already have the processor running at 1.5 volt in Amd overdrive but my stupid Bios has a insane low Voltage limit..

    Your Bios overvoltage is just fine... is will adjust +0.6v above the stock voltage. If you set it to +0.6v you would probably fry the cpu. :o
  16. r-sky said:
    Your Bios overvoltage is just fine... is will adjust +0.6v above the stock voltage. If you set it to +0.6v you would probably fry the cpu. :o

    WOW what the hell was I thinking you're right +0.6 would be 1.9V i only need 1.5.

    I don't know how such a mistake could happen I must have confused some numbers.... I put the overclock into the bios and everything works great.

    All my problems are solved the thread can be closed thanks again.
  17. I ran some more stability tests and the overclock is still not stable.

    I think its better to run the ram at ddr3-800 with 3600 cpu speed then ddr-1333 at 3500 right?
  18. Yes, the ram speed will have far less impact than the cpu speed. Although .1mhz isn't going to change many benchmarks, either. It sounds from what you've said that the entire system is more stable when the ram is at 800, and a stable system is always better than an unstable one, even if its a bit slower.
  19. The system is stable when I lower the multiplier by 0.5 resulting in a 3500 mhz speed (2400 Cpu Nb) with ddr3-1333.(prime blend is already up for 4 hours)

    I think I will try to increase the fsb to get something like 3570 Clock speed with ddr3-1333 stability wish me luck.

    Last time I tried 17.5x206 (Appr. 3620) I had a crash after 1hour 30 small ffts so I hope 17.5x 204 or something similar is possible.
  20. Now I'm running the cpu stable at 3.535 ghz (17.5 x 202) Cpu Nb 2424 and ram drr3-1346 at 8-7-7-20 Command rate 1 timings.

    4 hours prime blend without any error.

    I think I'm ok with that maybe I will tighten the timing even more but that won't have to big an effect on performance so maybe I'll just let it be.

    Tommorow (or some other day) I'll overclock my 4890 wish me luck there since my Cpu was a succer.
  21. You might be better off running the auto overclock utility in CCC. You won't set any records, but anything you gain above what it gives you wouldn't make too much of a difference.
  22. Woah! Turn off or disable ACC is in bios. This should clear up your problem.
    The PII has ACC built into the chip it does not need ACC on unless unlocking is needed. ACC on will cause instability in most systems running that have a PII. turn it off and see what happens
  23. No i need Acc to get the northbridge stable at 2400 and I needed a nb of 2400 to be able to reach a 3600 core clock.

    I've finished overclocking and the whole thing is stable thanks for your help.
  24. If you feel that it is a must than leave it. But I ask you to at least try it and see what you get.
  25. ACC gives no advantage when using a PII only on the Phenom I. It will usually cause instability in the PII pocessors.
  26. First I tried overclocking withouth touching the cpu-Nb. I maxed out at 17.5 x 202! then I read in Dolks guide that a higher Cpu northbridge helps reaching higher speeds. I could overclock to 2200 without Acc but still 18x200 was not stable...

    I also couldn't reach Cpu-Nb of 2400. Always core 3 error...
    In another guide I read that if you have a "bad" phenom II chip setting Acc to 0 on all the other and on +2% on the bad core might help. I tried that and could get cpu-np 2400 and then I could reach 18x200.

    Unfortunately when I overclocked the ram back to stock settings I lost stability (that's why I opened this thread) now If found out that I had to go back to 17.5x202 (3540) and a Cpu-Nb of 2424 to get the whole thing 100% stable.

    So the Acc is essential for the Cpu Nb speed, and the Cpu Nb speed was essential for higher overclocks.

    I've tried disabling Acc or any changes (+2 on another core which gave me errors) which always led to instant instability at Cpu-nb 2400.

    I've also tried to back the northbrigde down to 2200 without acc and reach a higher Cpu overclock but it wasn't possible.

    I think that I have a pretty bad chip, and I've reached the "sweet spot".
    Maybe it could get higher but I don't want to go over 1.5 V.

  27. Well then it sounds like you have done a good job at figuring out your problem. I think I would agree that you have a faulty Core 3 or it may be that you RAM is acting right, from the sounds of it changing the timings caused the instabilities. Have you run memtest? Have you tried OCing with only one stick of RAm or two.
  28. I have a bootable version of memtest but it always fails no after a few seconds no mather what ram timings I have (downgraded to ddr3-800 STOCK timings.). It even crashes when the system is rocksolig and passes 6 hours prime blend test. Maybe I have downloaded the wrong version of Memtest could you give me a link to a better one please?

    At the moment the system is very stable and has passed 5 hours blend test.

    The only mystery for me is why 3600 mhz was stable at ddr3-800 but wasn't at ddr3-1333. But I am sure that the problem wasn't a ram problem since at stock Cpu clock the ram was 100% stable and when backing down the multiplier by 0.5 again no ram problems showed.

    The problem also wasn't a Cpu-Nb relatet because I still run it at 2400 without stability problems.

    But I think there could be one problem. When testing the 3600 setting I always tested with Small ffts in prime I never tried Blend, maybe it was never really stable (although it past 6 hours small ffts). Another thing is that I had forgotten to enable round of checking which could have showed me errors.

    I have spent a lot of time and research with this overclock and I think that I've come to the limits of the cpu without passing 1.5V. I know it's not a great overclock but I do not want to invest any more money so if the ram was the problem I wouldn't want to replace it since this would cost money and I would in the best case only be able to increase the speed by 200 mhz or so.

    The only thing that I have left untouched is the Cpu Pll volage, I've read its the most dangerous to play with and doesn't help a lot.

    The ga-ma790fxt-ud5p isn't the best overclocker, neither is my particular cpu (otherwise 3700 would be possible).

    If you have any idea how I could reach a higher overlock I'm happy to trie it, but I know that the ram aren't the problem because they are rock solid after backing down 100 mhz, it must be a Cpu stability problem and after playing around with all the voltages except pll I've given up.
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