overclocking fsb unstable on new memory

z10m · 31 Dec 2008 at 22:58

Hi. I have E6850, XFX Nforce 680iLT SLI Moyherboard, Geforce 8800GT 512MB. 4GB DDR2 800MHZ. So my problem is that when i had cheap memory from ebay that would not work in dual channel mode i could overclock my FSB to 1666MHz (3,75GHz CPU). Now i bought OCZ 4GB (2x2GB) PC2-6400C5 800MHz SLI-Ready Edition Low Latency Dual Channel DDR2 and in dual channel mode my pc freezes even on FSB 1500. I cannot overclock as much as i could on cheap single channel memory.. Im very dissapointed as i paid for good memory.

porta · 1 Jan 2009 at 08:03

z10m said:
Hi. I have E6850, XFX Nforce 680iLT SLI Moyherboard, Geforce 8800GT 512MB. 4GB DDR2 800MHZ. So my problem is that when i had cheap memory from ebay that would not work in dual channel mode i could overclock my FSB to 1666MHz (3,75GHz CPU). Now i bought OCZ 4GB (2x2GB) PC2-6400C5 800MHz SLI-Ready Edition Low Latency Dual Channel DDR2 and in dual channel mode my pc freezes even on FSB 1500. I cannot overclock as much as i could on cheap single channel memory.. Im very dissapointed as i paid for good memory.

make sure you are running ram at correct voltage.

z10m · 1 Jan 2009 at 11:16

I was trying 1,85v 1,90v 2,00v and 2,1v. On 2,1v it appears most stable but also freezes after some time.. And if i run that memory in single channel my PC is running stable on 1666FSB on any memory viltage. So its only happening in dual channel mode..

gurusan · 1 Jan 2009 at 11:30

Have you tried nudging up your northbridge voltage

rapid64k · 1 Jan 2009 at 11:36

what slots are you using and what is your FSB in realtion to your memory FSB.

z10m · 1 Jan 2009 at 11:41

i'm using slots 0 and 2 for dual channel if i I stick memory in slot 0 and 1 it runs in single channel. Im using unlinked fsb so no matter how much i overclock fsb memory stays at 800MHz.. My system is running on 450Watt X-Power PSU but it was running stable with two 8800GT in sli mode on single channel memory. Right now I have only one 8800GT.

rapid64k · 1 Jan 2009 at 11:51

with my board I have to use slots 2 and 4 also looking at your your ram specs it says that they run at 800MHz. also what timings are you using? and what mulitiplier you using for your cpu?

z10m · 1 Jan 2009 at 12:06

on my board slots are numbered 0123 i tried slots 1 and 3 with the same resoult. Yes my ram runs on 800MHz and timings are 5-4-4-15 i also tried 5-5-5-15 and 6-6-6-18 with same resoult. CPU multiplier 9x

z10m · 1 Jan 2009 at 22:42

i just nudged up northbridge voltage to 1,5v looks stable on 1600FSB.. hope it will stay that way..

z10m · 3 Jan 2009 at 12:20

So do any one know if it's normal that system overclocks better on single channel than on dual.? And is 1,5v safe for northbridge because it is as far as my bios let me go.?

95thrifles · 3 Jan 2009 at 12:31

Sounds a little high for NB tbh
I know on older boards when you have all 4 DIMMs populated it makes OC'ing harder, you normally reach the upper limit sooner, so it would maybe follow that 2 DIMM's is less stable than 1, you could always try throttling back your OC a bit see if it stabilizes

rapid64k · 3 Jan 2009 at 13:27

1.5 is bit too high for NB try 1.45V as the very max.

z10m · 3 Jan 2009 at 14:31

95thrifles said:
I know on older boards when you have all 4 DIMMs populated it makes OC'ing harder, you normally reach the upper limit sooner, so it would maybe follow that 2 DIMM's is less stable than 1

i can overclock more with 2 DIMM's but in single channel mode (slot 1 and 2)
if I stick them to slots 1 and 3 (dual channel) its becoming unstable.