AMD AM3 Overclocking questions

[b1lk1]

OK, I hate to ask, but I have been out of the overclocking scene for quite some time and now that I have a PC again, I am OC'ing it to that last degree. I have the following:

AMD Sempron 145 with the second core unlocked
ASUS M4A88-TM
GSKILL 2X4GB PC3-12800 ram
HD6670 1GB DDR3
2 HD's
4 fans

This is stuffed into a small aluminum MATX case that has been modified by me for great airflow. While the PSU is only a 250W Seasonic, I have used a Kill-O-Watt to verify that it never pulls more than 150W at full gaming load so I am not worried there.

My questions are this. What is a safe northbridge speed? I just keep raising the HTT speed for my current overclock. @250HT I have a 3.5GHz OC @ 1.4V Vcore and I did bump up the NB to 1.2V. I am failing OCCT after about 45 minutes (not the Linpack). My temps never got over 49C (that is the socket temp, not the core temp). As you all know you can't read the core temps on an unlocked CPU. Northbridge speed is currently 2500Mhz. I keep reading it is safe top push it until it starts having instability, but I would love some clarification. Memory seems to not care it is being pushed far over stock speeds/settings, but I feel I may need to loosen the timings soon, although I'd rather sacrifice higher CPU speeds for fast tight memory.

I am using the stock cooler and it has yet to be hot to the touch after stressing it. Bear in mind I used to review heatsinks and overclock the hell out of my old S775 systems and even some AM2 stuff but I haven't done it for a few years now so while I want to make sure I get some useful advice, I am not a noob.

Please bear in mind that my PC is a budget build/gamer. It currently can run the games I play very well and I am not going to upgrade anything in the near future, although I may get a better CPU cooler when funds allow. I am looking to maximize what I have.

[sswilson]

Personally, on AM3 systems I've found that higher NB speeds (not HT) equate to a much "snappier" system, so you're on the right track by pushing for higher NB. That said, your 2500 might be pushing the envelope for your current setup.

Here's my current two rigs which are 24/7 folding stable.....

I've gone as high as 2700 on the 1090t, but getting that stable was a major pain in the butt, especially once you start throwing in 8G mem vice 4G.

Damn... I just realised that I've got exactly the same OC on each of those rigs with the only difference being the multi..........

[b1lk1]

Well, I just dropped the NB speed a touch, gonna try running OCCT again to see if that goes further and then go on to harder stress tests.

[b1lk1]

OK, put the NB speed back up (crashed quick when I changed it) and upped the HT voltage 1 click and loosened the ram to 8-8-8-24 and it is still going after 1hr. Looks like I am on the right track.

[sswilson]

Don't forget that there are two different NB voltages as well. Typically it's NB Voltage for one, and something to do with a "CPU - NB Link" for the other.

[b1lk1]

Yeah, gave both of those a .1V bump. Loosening the ram slightly did the trick, no problems after 2+ hours. I just restarted it and lowered the Vcore back under 1.4V as I had bumped that thinking it was the cause. Hoping to get lucky there as well.