See I have tried a LOT of voltage changes. And I mean a LOT. I ran in to this problem several months ago and just gave up. Now I am at it again because of my watercooling. In the end so far... lowering my vdimm has increased the amount of usable ram but I still need to keep fooling with it. Also, I use 12gb, but using only 6 changes nothing at all.

Part Number: 132-BL-E758-A1
Part Desc: EVGA X58 SLI
 
I already listed which bios worked it was the 1st thing i listed in my post it is : SZ2P.   or E758_SZ2P same thing.  
 
Im grabing a link http://cdn.evga.com/bios/E758_SZ2P.iso (is the bios I used in my E758)
The equivalent Bios for the LE version of the board would be the following : http://cdn.evga.com/bios/E757_S717.iso  This should be the one for your E757.  I have the E758.
 
I figured I would list exactly which bios worked correctly for me with a link for the iso to burn and the part number of my motherboard so there is no confusion. 
 
I tried the top 3 newest before this one.  All failed.  There may be a couple after this that still work.  I haven't located which bios that they actually broke it in yet, but this bios works for me at 4315mhz settings are 20x206 but with turbo it bumps it to 21x205.5 to 4315.  My ram is set to 2:8 at 821.9 (ddr'ed to) 1643.8mhz   i am running cas 777,24,74 with 1.65volts.
i tried alternating the uncore settings like someone posted and it didn't work for me i still had only 2 gigs of ram visable in the bios and in windows.  However windows 7 actually said i had 6gigs with only 2 usable simular to your situation.  The rest of my settings came from the old X58 overclocking guide on this very forum.  The only variance is i have a core i7 920 DO and the voltage i needed for the cpu was 1.375 to fully stabalize it.  It doesn't break 60C under load for temp. 

Alright, so I've tried everything mentioned and to no avail. Even the BIOS downgrade didn't work. Very upsetting. Now I may just return the Dominator RAM for some other sticks, which I really REALLY did not want to do. I don't understand why they just don't work with everything else in my system.

i am puzzled to hear of this problem and in a sense now glad i never updated the bios in my systems.

i  havent seen any memory vanishing....at the minute my systems using an E760 classy been to 4.0g with 6gb of G-skill (1.65v) 2000 pefect storm and bios version S61H...
 been fine and problem free.

only problem i had was with another board...it had a bent pin so stopped all the dimms slots being detected :( very easily done.
had 12gb G-skill (pi 1280) at the time and listed in the bios / black boot screen / and windows taskmanager only showed 8gb..turned out the bent pin was stopping the first 2 dimm slots. had to have it sent fo Rma

if the memory works in all the other dimm slots you can narrow it down to bent pin in cpu socket preventing 1 or 2 of the dimm sockets working.  apparently its very common when Rma 'ing.

either try the slots individually to determin if it the slots or memory thats faulty or try simular bios maybe that may help out.

oh and i found out the errors to reset my cpu and (or) ram setting in bios was  mainly due to the ram not having enought voltages.... my perfect storm wont boot properly and like yours gets this message about reseating unless i change it to 1.65..... check your ddr3 dimm voltages and vtt if on auto raise it a bit

GhostImage

Check out this thread http://forums.evga.com/tm.aspx?m=16223 there is some good info in there, maybe some will be of help.
Cheers :)

Hey, Ghost. I saw your thread a little while ago but I really don't understand exactly what you did. It's probably just me, I could just have a lack of understanding. Thanks.

I had the same issue after exceeding a CPU BCLK of 145. 2GB of my Ram became unusable. I tried almost every solution in various threads. Decreasing VDIMM voltage, increasing QPI, increasing IOH Vcore etc. What I did notice is that after setting my MCH Strap from auto to D:RAM Ratio, the issue was resolved. When setting MCH Strap back to auto, bam! I lost 2GB. SOLUTION: Set MCH Strap to D:Ram Ratio !

But my information is still relevant to the thread, Mod.

Anyone searching Google will find my post very helpful. Especially those searching recent dates.
The thread isn't locked. I didn't break any rules posting in it.

Scarlet-Tech

OphiX
But my information is still relevant to the thread, Mod.

Anyone searching Google will find my post very helpful. Especially those searching recent dates.
The thread isn't locked. I didn't break any rules posting in it.

Don't take offense to someone pointing out that a thread is 5 years old. That is literally all he did.

Oh, and he thanked you for posting. Usually that is a good thing, lol.

Thanks, I didn't know if the person making the post was aware of the age of this thread. Usually when you have good up to date info like this just make a new thread. 

Do you use a 32 bit OS?
Because a 32 bit OS is limited to 4gb.
Causing the additional 2gb to 'dissapear'.
 
 

I wonder if the op still has this computer 5 years later...