HELP!! 790i Ultra SLI Wont Boot with 8GB of RAM!
I have a 790i Ultra SLI Mobo from EVGA. I bought 8GB of DDR3 from OCZ's Reaper line. I have all the settings correct based on their 7-7-7 1.9v profile. Windows vista 64-bit will not load and give an error message that requires the system disk. Yet the windows system disk crashes to blue screen. If i run only 4GB vista boots fine and without a hitch. I have tried retarding the latencies and frequency and then windows starts to load but froze on the windows is loading screen. I am so frustrated! What do I do. The mobo says it takes 8Gb, but ti clearly doesn't. HELP!
MANUALLY set your voltages to the upper range for your RAM. MANUALLY set the timings. If you have a voltage drop control - enable it. Ensure the command rate is set to 2T, and that tRFC ("Refresh to activate delay" ) is 54 or greater.
If that doesn't work, you may need to raise the voltage to your FSB A Couple Steps, but no more. If you have to crank this up, go back and see what else could be at fault.
I agree with scooteq (though I'm not sure I understand the last statement about looking for what else is at fault if you have to up the MCH/Northbridge voltage).
To that point, on a different thread there was a good explanation of the potential issue that you may be facing. I'll include it here (I had saved this away so I don't remember who first posted it, otherwise I'd give them the credit due...).
You've run into a common issue (not mentioned above). Having 4 DIMMs installed at once is pushing the limits of current unbuffered DDR2 RAM technology. The control signals to the DIMMs get split among all of them, so having 4 installed means the signals to each are much weaker than with only 1 installed, causing errors. The better the motherboard design and the better the quality of the RAM, the less likely the problem, but once you have it, the only solution is to try raising the MCH (memory controller/northbridge) voltage a bit, perhaps 0.05V or 0.1V. This is NOT the DIMM RAM voltage (which you should have already set to the spec voltage specified by the RAM manufacturer for your specific DIMM part number).
I am a evga 790i enthusiast. I have had issues with memory. The 790i supports ddr3. I have run ddr2, and it only "sees" 3.6 gb like a x86 "32 bit" mode. This system is designed to run virtualization. I m running (3) gtx260s. Limitation? 8 gbyte .. that really shouldn't be an issue because the VirtualBox ... free vmware from Sun is not only free, but you can dynamically change memory etc. Running Microsoft as the "host" OS is like having a chaffeur drive your Ferrari. Suggestion ... and its free. the suggestion
1) buy pc10600 1333mhz 240 pin memory from Kingston, 2 (4 gbyte) kits. "lifetime warranty" you can get it from fry's or tiger direct. return your ddr2 to the yahoo that sold it to you. The 790i supports 2000mhz ddr3 but you can't really get there from here unless you OC to the gills. Don't OC anyway. Heat kills almost everything electrical. Watch your humidity and get a small ups.
2) download Centos 5.4 and use it as a "host" OS. its free
3) download VirtualBox from sun.com .... its free.... its easy reload vista on VirtualBox
4) download Open Office from sun.com .... its free
5) save your vista 64 bit key
6) buy a velociraptor drive 'makes a big difference.
7) buy a harddrive duplicator. $100 from Frys AluraTek
8) factory set your voltage params. If you have a voltage error it should post on boot
9) use firefox as browser if you need an explorer experience
ok so first before buying any ram you must check the mother board ram memory specs "the mother board lists memory types brands how many sticks and how much gigs in each stick it will handle. here is the 790i list
with in there you choose """Memory Compatibility List (1.56MB PDF)""""
here is the link
this tells you exactly what memory it can use and how many sticks of how many gigs and what brand, other than that,, alot of time is going to be spent in the timings and so on..
i my self found this out with my 790i bought 8 gigs of ram, they didnt meet the requirements, the meet the standard 667hz, 8 gigs, some other stuff power volatge and what not,, a while ago soo i put my 4 gigs back in the mobo and am going to buy some ram that matches the compatibility list