Why can't I overclock higher?

Mikesoft · 24 Apr 2006 at 14:35

In my sig you can see my current cpu (athlon 64 venice) and clock speed. However I cannot clock the cpu any more than 2.5Ghz without everything becoming unstable. Is there anyway I can sort out this problem or have I reached some kind of cpu limit?

Mike

Darkwave · 24 Apr 2006 at 14:47

I'm finding that 2.6GHz is the limit on mine (from 2.4GHz) and that's not even entirely stable (55min tops in Prime95), just "stable enough."

My problem is my cheap-o motherboard and RAM, I cost-cut and went for a GA-K8NE and Corsair Value. What memory are you using at the moment?

Mikesoft · 24 Apr 2006 at 15:01

I had to cost cut and go for the OCUK ram. Could that be the problem?

Darkwave · 24 Apr 2006 at 15:20

Cheap anything seems to affect overclocking from what people have told me. I know it's why I am clocking crap, lol.

Chiribo · 24 Apr 2006 at 15:52

My guess, is that you haven't put a splitter on the RAM and therefore you're increasing the FSB of the CPU & RAM over 200 at the same time.

You can do the above in the BIOS.

Also have you done the rest like decreasing the HT multiplier? Maybe incresed the voltage a bit on your CPU? Have manual memory settings for the RAM for when it goes above a certain speed?

I can get my 3000+ venice to 2.6GHz however if I do that the ram would end up @ below 200MHz, where as at the mo it's running on 2.45Ghz and ram is at about 223MHz with 2x512MB of some Hynix ram and 2x512MB of TwinMOS ram

Darkwave · 24 Apr 2006 at 15:56

I'm guessing he's done all, or at least most of that, because he would've had a lot more trouble getting to 2.5GHz. Could just be that he's gotten to a limit with the RAM etc. and temps that he has. :confused:

I'm a n00b to this myself, so don't take my word as gospel.

Mikesoft · 24 Apr 2006 at 16:08

I dunno if I have done all that! I am still fairly n00bish to overclocking

On cpu-z I get these results:

CPU
Voltage: 1.424 (goes up to 1.440 sometimes)
Stepping: 2
core speed: 2500.3
Multiplier: x10.0
HTT: 250.0

MEMORY
type: ddr-sd ram
channels: dual
size: 1024mb
Freqency: 250.0
CAS Latency: 2.5
Ras to Cas delay: 3
Ras precharge: 3
cycle time: 8
bank cycle time: 11
Dram idle timer: 16

Darkwave · 24 Apr 2006 at 16:13

You need to tone down your RAM, it's running at DDR500 mate. Put it at 166MHz (DDR333 effective, but it'll be faster with the increased FSB.)

Mikesoft · 24 Apr 2006 at 16:27

In the bios it said it was running at 200mhz (ddr400)

Darkwave · 24 Apr 2006 at 16:31

Yeah but you need to lower that because it all acts as a part of an equation in working out the final speeds. It'll say "200MHz" in the BIOS, but it's really 250MHz because the FSB has been increased so you should keep an eye on it with CPU-Z and get it back down.

You need to get that RAM speed back down to 200MHz or lower, as it's running at 250MHz (DDR500) at the moment, which is no wonder it's unstable. In BIOS set the memory speed to 166MHz and it should clear right up, it may drop below 200MHz in CPU-Z but it's better than being over.

I've set my RAM divider to 166MHz but my DDR400 RAM is still running at 175-ishMHz (DDR350) because of the increase of my FSB to 216MHz among other things.

Mikesoft · 24 Apr 2006 at 16:36

Thanks for the info!

ok, I have done that now and cpu-z says the freqency is now 208.
When I had the ram at 200mhz the system was not unstable at all, all my games and stuff worked fine.

Do you reckon I clock the cpu higher now?

thanks

Darkwave · 24 Apr 2006 at 17:08

208MHz should be reasonable, but if it's still unstable then it could be that the voltage for the CPU is too low. I am not going to tell you that though, because I don't have a clue when it comes to voltages etc. and had to ask here when I was doing mine (eventually finished at 1.7v relatively stable.)

You can try going higher with the FSB but you'll find you will have to put the RAM speed down again (maybe even to 133MHz) to compensate.

Mikey1280 · 24 Apr 2006 at 17:10

Yep, turn the LDT multiplier/HTT multipier down from 5 (1000 on some boards) to 3 (600 on someboards). Then raise the FSB, its not stable give it some more volts.

Darkwave · 24 Apr 2006 at 17:13

Mikey1280 said:
Yep, turn the LDT multiplier/HTT multipier down from 5 (1000 on some boards) to 3 (600 on someboards). Then raise the FSB, its not stable give it some more volts.

Oh yeah, crap. I completely forgot about that.

My board is a 754 so it's 4x at stock, I had to tune it down to 3x or it wouldn't even boot. Try that OP.

Chiribo · 24 Apr 2006 at 18:23

If it's a venice then it's 939, my board goes upto 273FSB with a HT multiplier of 4 which overall equals the ram fsb of 223.8 (¬_¬) at the moment, and I've currently got the ram runing from pc166 speed.

So in theory, if you put in a ram limiter at 166 (333) and your ram can go upto 250FSB regular, then the FSB you should be able to achieve on the CPU is very close to 300, well in theory anyway

I also remember reading that if you take the FSB over 300, turn down the HT multiplier to 3. Also maybe increase the voltage on the CPU a bit as well, well if the system becomes unstable anyway.

On a further note, when testing stability, something that I learned about while I was recently re-overclocking my new mobo, is that when you're running prime, do the Torture Test and tell it to test the Small FFTs and leave that runing for some time in order to test how stable the CPU is.
When testing the stability of ram, what gave me the fastest result was running memtest, and mainly running test #6 if it passes test #1. For me personaly, that's where most of the errors showed up when it was the RAM that couldn't handle the presure anymore

Hope all that helps!