so i recently started using my cousin's previous gaming pc to do some gaming of my own. i knew i'd have some issues since it's pretty dated and i'm hoping to play fallout 4 on it which is a relatively taxing game. got it set up and everything ran pretty well considering it hadn't been used in probably a year.
anyways, i bought some memory since it only had 2x2gb corsair dominator gt sticks (1600 mhz, 7-7-7-20) ddr3 and the minimum recommendations for playing fallout 4 are 8gb of ram. i haven't seen it use anywhere close to 8gb yet, probably maxing out around 3.5gb from what i have seen through Windows Task Manager (with new RAM) but before getting the new memory, the game was stuttering constantly basically making it a slideshow during combat. 

So what i did is bought 2x8gb sticks of DDR3 Corsair Vengeance 1600 mhz 10-10-10-27, inserted in place of the old memory and got an error on start up not recognizing the hardware. i turned off the pc, kept the 2 8gb sticks in place and added the 2x2gb old sticks in the remaining 2 slots, pc started fine and CPUZ recognized 20gb of RAM inserted. was able to play fallout 4 without issue for the last week and a half- 2 weeks without issue. 

couple of days ago, i started getting the blue screen error hinting that it's a memory issue, random pop ups saying that windows wasn't working and shut down, and my computer would restart randomly. the blue screen said to check and make sure new hardware or software is installed so i messed around with the memory, making sure everything was in place properly and the only way i don't get that error anymore is with the original 2x2gb sticks of Corsair Dominator gt installed by itself. i'm honestly at a bit of a loss as to why it would run smooth for nearly 2 weeks and now start giving me issues. drivers and BIOS are all up to date- at least as up to date as possible. they're old components and haven't received updates in some time so that could be part of the issue in itself maybe?


specs are:
intel core i-7 860 2.80 ghz,
mobo: EVGA p55 sli e655gpu: Ge Force GTX 1060 6gb
memory: Corsair dominator gt 2x2gb ddr3 (1600mhz 7-7-7-20)
Corsair vengeance 2x8gb ddr3 (1600 mhz 10-10-10-27)
OS: Windows Vista Ultimate 64 bit
 
any advice, suggestions, etc. would be greatly appreciated. i plan on building a new pc and salvaging a couple parts like the power supply, gpu, case but was hoping i'd be able to put it off for a while considering everything had been running pretty well up until just the other day but i'm kinda lost right now. thanks!

thank you for the suggestion!
here is what i've done so far (admittedly not much but i'm not sure exactly what it is i need to manually change with the RAM settings inside the bios, and what to change the settings to):
 
powered down pc, unplugged everything, removed old memory sticks and inserted Corsair Vengeance sticks into the previously occupied slots, plugged everything back in, reset CMOS, hit DEL to enter bios.
from there, the screen shows CMOS settings wrong, CMOS date/time not set, press DEL to run SETUP, Press F2 to load default values and continue. I hit DEL, it takes me to the setup utility,  i go to frequency/voltage control, then memory configure, and what i get is shown in the attached image but i'm not sure what to change or what to do from there.
 
is it possible that the mobo simply can't use 8gb RAM sticks? i know these corsair vengeance aren't on the compatible RAM list on this site but neither are old memory (Corsair Dominator gt) and those worked fine.
 
anyways, again thank you for the help. greatly appreciated
 
edit: forgot to mention what happens after resetting CMOS and entering BIOS, the picture i attached shows that it's recognizing the speed and frequency of the new RAM as far as i can tell, so all i did is hit f10 to save, it exits out, the computer restarts and i get a quick blue screen error that just flashes on screen and eventually a windows error recovery screen that says "windows failed to start. a recent hardware or software change might be the cause." i will attach images of the blue screen error and windows failed error as well in case that might help

thanks, Sajin. sorry i just got done editing my recent post. after saving with those settings the computer restarts and continues to loop from blue screen error, to windows failed, tries to load and then starts over again
 
edit: will double check the voltage. thanks!

should i change that for the bootup cpu vcore and eventual cpu vcore, or just the bootup? it's currently at 1.1685v

ok so i've increased bootup by .09 and eventual by .10. still having basically the same issue, although different information on the blue screen now

there is QPI Frequency selection which is set to auto currently, and i can change it to either 4.270 GT/s or 4.800 GT/s
 
there is also Current VTT set to 1.050v (greyed out/unselectable) and beneath is bootup CPU VTT and Eventual CPU VTT, both set to auto which is, i assume 1.050v. Increase both by .10?
 
don't see anything labled Uncore or QPI. I'm looking at the correct thing though, right?

changed bootup and eventual vtt by increasing voltage .09 and .10 respectively, and the computer keeps resetting almost rapidly now. i get a quick blue screen that literally flashes then disappears and takes me to windows error recovery where i can choose to start in safe mode, safe mode w/ networking, safe mode w/ command prompt, last known good configuration (advanced), and normally (which just restarts the computer and shows an image saying P55 SLI, then blue screen flash, then windows error recovery)

just tried entering safe mode and the screen is entirely black except for the mouse pointer/arrow. it had been working previously (as recently as monday or tuesday morning) although i didn't do anything in safe mode when i had entered previously
 
i'll try restarting and entering safe mode again

Ok, at this point I'm going to recommend that you try booting into windows with each stick of ram individually.

willyb9
normally or in safe mode?

Normal.

So you tested both individually and only one stick successfully booted into windows?

If the one you're currently using blue screened at first then it's most likely the defective one if the other one works perfectly without a problem.

Got it. So when I told you to test them individually you took the one out of slot #3, and only tested the one in slot #1, and it blue screened once then started working without issues?

Yes, there could be a problem with slot #3, or the cpu may need more voltage to get both to work properly.

I'd try running memtest on both sticks again individually in slot #1 just to make 100% sure they are fine. Run memtest on each stick for 3 passes. If they both pass without errors you'll know they are fine, and that it's a problem with slot #3 or the cpu needing more voltage. Booting both sticks in slot #3 will tell you pretty quickly if slot #3 is messed up or not.