Just over clocked an E6420 from stock 2.13 Ghz to 3.1 Ghz and ran it stable for an hour on small FTT in orthos. I haven't done a ram test yet because of a few things I was hoping you guys could clear up for me:
Firstly, I am running an asus p5n-e motherboard, and they are notorious for not liking 4 gigs of 800 Mhz ram, which is what I have in there (Corsair XMS2 6400 DDR2, stock volatge tested 1.9V timing 5-5-5-12). The mobo would accept 1, 2 and 3 gig but when the forth one went in it just wouldn't boot or would freeze up even when in BIOS. I heard tweaking the voltage helped this issue so with 1 gig in I pushed from 1.9 to 2.1V and it liked it after that.
Ok, so I oc'd to 3.1 Ghz, pushed the Vcore up sufficiently, but it wasn't stable, I pushed the Vcore up further again but was still getting crashes. As the RAM wasn't stable at stock voltage and needed a push just to work at stock I thought that maybe it was the RAM giving me the issue (or more the mobos ram contoroller), I pushed the ram up to about 2.17V. The system was stable then for a good hour or so, then a BSOD while gaming. I slowly increment the RAM again, each time getting longer stability, until at about 2.2V I have had no crashes on small FFT in orthos or while gaming.
Like i said I haven't stress tested the RAM for fear of frying it as 2.2V seems a little high. I have pretty good case fans and a Zalman 9700 on the CPU and it never gets hotter than 55C.
So I was thinking that maybe due to the specifics of this motherboard the RAM isn't actually getting the right voltage as given in the BIOS, as in the RAM is tested at 1.9V, but even with that setting in BIOS it wasn't getting enough potential. So I am hoping that the 2.2V I have it working at now in the BIOS isn't actually 2.2V at the RAM and is something a bit lower, because well it hasn't cooked yet :s
The ram is just running in sync with the CPU, FSB is at 387 Mhz so my RAM is running at 774 Mhz.
Does anyone know if this is ok or know of a good way to test my RAM without cooking it or can anyone offer any suggestions or had similar experiences with this mobo or another? I did extensive reading on the on the E6400 and overclocking it before doing it, and I have seen many examples of it going to 3.1 Ghz with an aftermarket cooler with 800Mhz RAM, but yeah, this mobo problem with not liking 4gig RAM at stock voltage has me worried that I may have the memory voltage up too high...
I was going to increase the northbridge voltage but i couldn't work out what it was set to stock, BIOS doesn't tell me and I couldn't find the info anywhere.
On a scarier note the RAM is actually at 2.3V in BIOS :s, but it has been stable for days now and the RAM isn't hot, this would normally worry me but I think the memory controller on the mobo isn't quite right, as it say in BIOS the RAM is running on 2.3V, but CPU-Z says the RAM is getting 1.8V. I am not sure which reading to rely on, but as the RAM needed to be pushed to over 2.1V volts in BIOS just to run at stock I have a feeling the mobos memory controller is not giving the voltage set in BIOS to the RAM when all four slots are filled with 1gig sticks, but the voltage is being divided amongst the RAM or a smaller voltage is actually being sent.
I will try look for what the NB is set to stock for an E6420 and try dropping the RAM voltage while increasing the NB voltage and see if I can keep it stable, but i dont have that much cooling on the NB so i dont want to overheat that either...
Thanks again and please post any further suggestions if you have some!
I tried to tweak the north bridge voltage and lower the RAM voltage but I couldn't get any stability out of the system, I think because to get 4 gig of RAM running at 800 Mhz on an p5n-e mobo quite a high voltage is required for some reason.
The RAM was getting really hot which was expected so I took the 4th stick out, lowered the RAM voltage to 2.1V and set the north bridge back to auto and the system is very stable now with the processor running at 3.1 Ghz. I guess you just cant run 4 gig at anything over 667 Mhz on this board for some stupid reason...