Overclocking a 939 Athlon 64 3800+

So I'm having the most hellish time with this. Im running on a AMD Athlon 64 3800+ with 1024MB of Crucial Ballistic DDR400 ram running at 2-2-2-6 1T. I am air-cooled with 4 case fans and stock HSF.


My CPU seems to bottom out at 210(core) * 12(mult.) for 2520. HTT at stock(5). I have the VCore at 1.4750 and the VDimm at stock(2.6000). This is the point where it is 99% stable. I can run Prime95 indef. and Super-Pi the same.

I can't seem to get past this limitation at all. This is my first time OC'ing an AMD as I usually use Intel... I didn't think it would be this difficult.

Can anyone give me any ideas?

I am reading up on Memory timings and I was thinking of trying to run the memory at 333 instead of 400. Or relaxing the timings a bit. But Im still not POSITIVE of how that would affect my CPU.

My goal is to hit, or get as close too, 2600 as I can.

Here is some pictures to give a better idea:

Lower you HT multiplier to 3x or 4x. THats very likely your problem, as its is sending the HT Link over 1000mhz causing instability.

Edit: In fact take that back, your HT link appears to be fine in the screenshot

Rereading your post, I don't think you quite understand how the RAM and the CPU work in an AMD system.

YOur RAM is likely what is causing the instability, not your cpu. 2,2,2,5 are very tight timings so I wouldnt be surprised if your RAM couldnt go further than 210mhz with them.

Use the Isolidate and Consolidate rule. Put your RAM on a strong divider (2:3 or whatever) and up your fsb until you cpu reaches its limit. Then do the same with RAm at different timings (giving the cpu a smaller mulitplier obviously) to see what its max is.

Then you need to find the best balance between the two

I hope that helped and is readable

I tried at 3x and It hit the same bottleneck at 1 increment higher on the FSB higher and it wasnt stable.

Havn't tried 4x but I assume it well net the same results.

Also, throw on that 166mhz divider as well.. this will warrant a lot higher HTT which equals more CPU mhz.


Good Luck and let us know your results!

166 diveder is the equivilent of 333mhz at DDR I assume. I'll give that a go. I shouldn't need to lossen the timings while on the divider though, correct? As the memory would be topping out.

legendz411 said:

166 diveder is the equivilent of 333mhz at DDR I assume. I'll give that a go. I shouldn't need to lossen the timings while on the divider though, correct? As the memory would be topping out.

Click to expand...

No. . .unless your ram is faulty. (e.g. cant run its stock timings, maybe try a memtest to check).

Also, have you locked your PCI frequency to 33.33mhz?

I havn't looked to see the PCI frequency. I did see the PCI-E choice though. It is on Auto. But I will look again for PCI. It should be locked too 33 (or 33.3). Yes?

I will boot into BIOS quickly and take a look see.


EDIT: 133 divider is 2/3 apperantly. Not a direct transformation. E.G. 200mhz is a 1:1 divider?

the ratios set the cpu/x speed... x = ceiling( cpu multi / memory ratio)

see sig

Ok. I locked the PCI at 33.33. So thats done. Just for the record, I AM running on a 4x HT. I will go apply the divider now and start OC'ing again to see where that gets me.

Lower your HT to 3x, that way it won't top out while you find your CPU max

Aight. I put my memory on 266mhz (133). On CPUz it reads CPU/18 and Clockgen says ram is at 140, which is 2520/18. So everything is going allright there. I'll lower the HTT from 4x to 3x and then start upping the CPU.


I run Prime95 lvl 3 torture test for 15mins before I push my CPU farther. And it did not error. So I will continue to push. How far should I expect to get on stock HSF and moderate case cooling? I will most likely NOT go past 1.5 VCore, if that. Trying to stay under 55c at 100% load.

I've gotten my CPU to 2616 ( with my ram at 2.5-3-3-6 and a 133 Divider. I've acheived my goal

Thank you, those that helped me out. I learned much more by being hands-on then I have reading guides for a long while.

It ended up being 218 * 12 = 2616. I wondered if lowering my Mult. would result in a faster Core (238 * 11 = 2618) For example. That would be a faster overclock then 218 * 12 = 2616, correct? As my core would be actually faster.

If I were to lower the Mult. and raise the Core, would I have to modifiy anything on the RAM? It should be the same as the frequency of the CPU isn't changing on the whole right? The cpu would draw more power though, wouldn't it, and at 1.4875, I can only go up one more step before I will stop feeding it power.