Vista Tutorial - Vista x64 BSODs on Resume from S3 Standby

I know this is not uncommon, but I'm hoping someone will see this who has successfully resolved the issue. I'm getting BSODs when resuming from S3 standby (sleep in Vista). The time from resume to BSOD is usually just a few minutes, but sometimes the system will run until shutdown, then crash on shutdown. Otherwise, everything seems rock solid. Just cannot resume from S3 without blue screen eventually. The blue screen info is different each time: IRQL_NOT_LESS_OR_EQUAL, MEMORY_MANAGEMENT, etc.
I have Memtested both banks of memory for over 10 hours several times with absolutely no errors reported. Runs benchmarks and every app I throw at it no problem. I have the latest drivers and BIOS from Gigabyte and Nvidia, all the updates from MS.
If I remove 1 DIMM and fall back to 2GB, the problem goes away. It appears the 4GB of RAM is making my system unstable. Anybody have any clues??

Gigabyte GA-P45-DS3L BIOS F7
E7200 Core2Duo 2.53Ghz 1066Mhz FSB 3MB L2
SuperTalent 2x2G DDR2-800 PC6400 CL 5-5-5-15 (T800UX4GC5)
Seagate 500GB SATA2 7200 32mb HD
EVGA 8800GT 512MB Superclocked Edition
Ultra X-connect X2 550-watt
Vista x64 SP1

Anybody else having trouble getting Vista x64 to work stably with 4gb of RAM?

My setup is significantly different than yours, but I have no issues with 4 GB RAM (2 x 2 GB). I even did not run into the issue of having to remove 1 stick for installation like a lot of nVidia nForce based motherboard owners did....

I can say this though - check your voltages for your CPU and RAM and stuff and if the motherboard BIOS allows for overvolting, start experimenting by incrementally increasing them. Also, see if there is any active cooling on the northbridge, as 4 GB of RAM runs that puppy up pretty hot - I have manually set all my system fans at 100% 24/7 rather then having them incrementally increase based on temps - it keeps it cooler that way and my system is stable at a ~33% OC at 3.21 GHz from 2.4 GHz.

Well, I have the RAM voltage at 2.1v, as per spec, and probably shouldn't push that any higher. Not sure if bumping up the CPU voltage could make a difference, but perhaps I'll try that.
I doubt overheating is an issue, as I can run 3dMark06 and tons of benchmarks for hours with no problem, while on the other hand, I can cold boot, put it in standby, wait 3 minutes and resume, and it will blue screen.
At this point, I'm afraid I'm ready to give up...time to RMA both board and memory and try something else.

I can also tell you this - I have my CPU OCd to 3.21 GHz (1428 FSB) and it works perfectly. If I bump it to 3.375 (1500 FSB) I get the exact same symptom - absolutely *no* other changes other than bumping the FSB.

My CPU is overvolted to 1.45 V, and my RAM is running just under spec at 5-5-5-18 @1000 when it is rated at 5-5-5-15 @1066. I have it overvolted (according to the BIOS) at 2.0 - OCZ says 2.1 is spec but many people can get it lower than that so I settled for a happy medium of 2.0 where it remains stable....

So you are getting the "BSOD after resume from standby" problem, but you can fix it by adjusting your FSB speed??
I'm open to suggestions, having tried every permutation I can think of and getting no results from Gigabyte or Super Talent.
Almost all my testing has been at "stock" settings: 266 fsb, 9.5x multiplier -> 2.53ghz on the cpu, DRAM speed at 800mhz, timings as per SPD (5-5-5-15). The only thing I have adjusted is DRAM voltage to 2.1v, as per spec and Super Talent's suggestion. Though I have run it at 1.8v, 1.9v, and 2.0v and I still have the BSODs on resume from standby as long as I have both sticks in.
At this moment, I have OC'd to 400mhz fsb and 8x multiplier -> 3.2G on the CPU; haven't adjusted CPU voltage - always at 1.25v Vcore ; memory is 800mhz, 5-5-5-15, and 2.1v.
Any suggestions to try?

essentially, yes. Although I did not try dropping the multiplier in my BIOS for my CPU to see if I can achieve a more stable OC....

And apparently I need to have a rather high voltage for my CPU at the speeds I am clocking or else it goes goofunky....

It's interesting that my system is so stable with vcore at 1.25v, but maybe going from 2.53 to 3.2G just doesn't need any more? DRAM definitely needed to go to 2.1v.
Meanwhile, I'm using Hibernate instead of S3 standby, and things seem fine - no BSODs. Other than that, the system runs everything I throw at it, and temps never go above 55C realtemp. I could probably push the OC more, but it's blazing fast as it is, and I don't want to push the temps. My cooler is not that fancy.

Actually, the Vcore setting is on auto and gets set to 1.375v by BIOS. My mistake...

For anyone else who is experiencing this problem, there is much more coverage here:
GA-EP45-DS3R unstable after sending to S3(STR) sleep state - TweakTown Forums
This is a Gigabyte-specific forum, but any input on the issue would be welcome.