hi, for the last 2 months or so, when i upgraded from 2GB to 4GB i have been having BSODs in Windows Vista x64 SP1, and also in Windows XP Pro x32 SP3, though mostly in Vista. they occur mainly when gaming, and i cannot figure out why.

i have tested the RAM with memtest86+ numerous times. with all 4 sticks in, 1 stick in each slot and 2 sticks at a time. no errors were found. i did the same with the Windows Vista memory test, also no errors found.

i have been reading about this and it maybe that the voltage isn't set high enough, but i do not really know how to change this as i have never changed RAM timings or anything to do with overclocking.
i have read that if the voltage is set too high that it can fry the memory. and possibly also the motherboard RAM slots.

i have tried to find the specifications for my RAM and motherboard, but i haven't been able to. Asus doesn't have any info on what voltage or timings are required to run RAM at 800MHz. Apacer doesn't have info on it either. i am stumped as to why i keep getting BSODs.

my specs are;

Intel E6750 Core2 Duo 2.66GHz
ASUS P5K
Apacer 4GB DDR2-800
GeForce 8800 GTS 640MB
ViewSonic 19" WS (2ms)
Realtek HD Audio (on-board)
WD SATA 320GB HDD x2
LG SATA 18x DVDRW x2
Thermaltake 600Watt ToughPower PSU
Thermaltake Soprano Case

edit: here is the link to my RAM

http://ap.apacer.com/ap/products/s [...] &sStatus=A

Your RAM may be defaulting to 1.8v in BIOS. In BIOS, set the RAM voltage to 2.0-2.1v for PC6400. Instructions are in your ASUS manual. With 4 DIMMS, you have to also increase the Northbridge voltage to 1.45-1.5v. Doing this will likely cause the system crashes you are experiencing while running software applications to stop.

is it safe to change the voltage from 1.8v to 2.0-2.1v? and the Northbridge voltage to 1.45-1.5v?
note i have not done this before so i am not too confident about it. i will try it according to the instructions in the manual.

edit: in the manual the options for Northbridge voltage are

Auto
1.40v
1.55v
1.70v

Open the ASUS Probe and check your NB voltage. Default will be 1.3v or so. Increase it slightly. Same with the RAM voltage. 2.0v will not hurt the RAM. See if you can get the system to stabalize with a slight voltage increase. That's what the BIOS adjustments are for.

i think i found the entry in the motherboard manual that is about the RAM voltage.
the configuration options for DRAM Voltage are:

Auto
1.80v
1.85v
1.90v
1.95v
2.00v
2.05v
2.10v
2.15v
2.20v
2.25v
2.30v
2.35v
2.40v
2.45v
2.50v
2.55v

it states underneath this:

the RAM didn't come with any documentation so how am i to know what the recommended voltage is?

edit: i am not sure if this is relevant but under the Northbridge Voltage configuration options in the manual it also has Northbridge Voltage Reference. the configuration options for this are:

Auto
0.67x
0.61x

i do not know what this means, but it also refers to the Northbridge.

Have you gone into BIOS? Also, open ASUS probe and check what the RAM and NB voltage are set at currently. Increase the voltage in the smallest increments if you want to. Setting. the RAM voltage to 2.0v for PC6400 will not damage the RAM. If the NB voltage is set to 'auto' in BIOS, chage it to 'manual' and set the voltage manually that way. Again, that's what the adjustments are there for.

not yet. thanks for explaining. the motherboard manual doesn't really do a good job of that. it just says what you can put the settings to. i will try it in the smallest increments available (.05).

edit: i have tried the Asus Probe II on the motherboard CD, but that doesn't have any RAM or Northbridge voltages listed. just the CPU Vcore and the 3.3v, 5v and 12v voltages and the fan speeds. i have looked on Asus's site but they do not have an updated version of the utility!

notwithstanding the good advice from Badge,,you should be aware that "some" mobo's do not play well with 4x1 ram,,and check the QVL [qualified vendors list] for your mobo, i had a similar problem with an asus p5k and ram,got rid of the asus mobo....

the RAM i have isn't on the QVL, (i found that out yesterday, 8 months after i bought the motherboard and computer components)

edit: is there another program besides Asus Probe II that can tell me the RAM and Northbridge voltages?
i have tried Speedfan and i had issues with that. and RivaTuner with CPU plug-in was even worse.

further edit:

i checked with Everest Ultimate Edition and it says the Core Voltage is 1.25v. is that a bit low?
it doesn't tell me the temperature in there though.

in SiSoftware Sandra i found the voltages in there listed as 1.80v for all four sticks. but again, doesn't say the temperature for them.

i have not gone into the BIOS yet as i am afraid to change anything i am not sure of.




edit: i went into the BIOS and changed the Northbridge Voltage to 1.40v, the DRAM Voltage to 2.00v and made sure the CPU Voltage was on 1.3v (it was on Auto so i changed it to 1.3000v).
now here is the weird thing. i checked in CPU-Z, and Everest. the only change that stuck was the CPU Voltage. the Northbridge Voltage is still at 1.25v according to Everest and the DRAM Voltage is still 1.8v according to CPU-Z.
in CPU-Z before i went into the BIOS the CPU Voltage was reading as 1.184, 1.192 and 1.200v. it is now reading as 1.264 and 1.272v.
i went to check that the multiplier is set to 8x, it said it was but in CPU-Z it tells me it is set to 6x and it is only showing 2003.8MHz as the CPU speed when it should be 2666MHz.
i am getting conflicting readings, what is going on here?

i tried Asus Probe II and i keep getting this error:



the same issue i had with it the very first time i used it last year.

okay, it's been a few days and i have finally found an alternative to Asus Probe II that will show me the Northbridge temp.

NextSensor.

my Northbridge temp is 31 oC in the green. is this a safe temp? i have never seen a Northbridge temp before so i do not know whether it is high or low.
the program has a setting for vdimm though it stays on 0.000 all the time. i don't think it is reading it, i know for certain that i have changed it to 2.00v but it isn't showing me this. also is there a way to monitor vdimm temperature?

31C is perfectly fine for a Northbridge.


Regarding your fluctuating readings - That is from a power saving feature called SpeedStep. You can disable it in the Bios (Speedstep/EIST), if you want.


On your RAM - Check the timings and voltages, and Manually set them to the maker's recommended. Make sure the Command Rate is 2T. And check that tREF is set to 54 or higher.

umm... what is tREF? temperature reference, timing reference? could you elaborate on what this means please?

tREF is the refresh rate. The abbreviations may not always be the same: Your Bios may have a setting like "Refresh to Activate Delay", or something like that. With more memory, the computer often needs a looser setting.