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AMD phenom ii 945, asus mobo, corsair ddr3 1600 ram, won't post, ugh!

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June 13, 2009 5:08:08 PM

Built a new system, cannot get it to post.

650 watt psu, AMD phenom II 945 which is the AM3 chip, yay, 4 x 2gb of Corsair xms3 ddr3 dhx dual path which is supposed to be running at 1600 and an Asus m4a78t-e motherboard. There are going to be other parts and pieces in the machine but I have not even installed them yet to simplify trouleshooting at this point. So it's onboard viddy, a cd-rom, nothing else.

Boot it up, BIOS prompts me to F1 for setup or F2 to go with known values. If I press F2, says it cannot detect a boot device and fails. (I'm not even trying to install an OS yet, just wanted to run memtest86 from the CD and make sure all the ram modules are working.)

If I press F1 to go into bios to edit settings, I don't even have to change anything, just accept what it arrives at via auto.

When the system reboots, I no longer even get the change to see the "press F2 for bios", it just gives me a black screen.

If I use the jumper to reset the cmos then I can boot the machine and see the prompt to set my cmos. Set it and the process repeats.

I have no frickin' clue as to what could be going on here. Bios detects cpu and all four sticks of ram just fine. I tried removing all but one stick and tried booting each each of the four sticks running singly in the orange slots on the board. Did all four, same problem every time.

I have a *suspicion* that maybe the RAM is too fast. I've seen commentary that the 1600's are supposed to be supported but often need to be run at 1066 for stability. But the indication is that the system would appear to run fine but have random problems, not fail altogether. All the same, tried underclocking the ram via the overclocking interface, no joy on that.

Seeing as I cannot even boot into an operating system, I am unable to flash the BIOS if this is indeed a BIOS problem. I've seen discussion on the net about modern motherboards and ddr3 having problems at times. Sometimes the CPU doesn't support what it should, sometimes the motherboard doesn't, and sometimes the ram misbehaves.

And just for giggles, left it running at the bios screen to monitor the temps. After about 15 minutes of operation at what I hope would be idle, cpu is 89.5f/32c, mb is 95f/35c. Installed the cpu heatsink with recommended thermal compound and everything appears fine but heat problems should show as instability after the system's been on for a bit, not what I'm seeing right now. (or not. never can tell with these beasties.)

At this point I'm pulling my hair out. I've tested everything I can think of. Please let me know what you think the solution might be! Thanks.
a b B Homebuilt system
June 13, 2009 5:14:16 PM

Did you try a single memory module or memory that's on the QVL?
June 13, 2009 6:35:34 PM

Well, there's an update. I haven't messed with hardware for a while, most of my computers are usually built. :)  Turns out that you can flash bios via a cd-rom tool. Burn latest bios to cd, use bios flash utility, flash bios, reboot, all is almost fine. I can run memtest86 and everything fine on one stick, the computer lives. But if I put in all four sticks I get the same problem. UGH. So I have no idea what I'm looking at here. The previous behavior must be the spoken about "when in doubt, cut power to cpu to not burn it out" feature. The bios was from jan of this year but the 945 must have been too new for it. The bioses available on the cd-rom weren't any newer which is why I had to download the new one.

So now I need to figure out if there's a compatibility issue between 3 and 4 sticks on this system. UGH!
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a b B Homebuilt system
June 13, 2009 7:32:44 PM

Unfortunately you didn't check the QVL before buying your RAM. 1600 MHz modules are supported in one or two slots only. A single Corsair 1600 MHz module is supported, but it should support all 4 modules at 1333 MHz and 9-9-9-24 timings. Depending on the modules, 1.5V to 1.7V is required.
June 13, 2009 7:39:20 PM

GhislainG said:
Unfortunately you didn't check the QVL before buying your RAM. 1600 MHz modules are supported in one or two slots only. A single Corsair 1600 MHz module is supported, but it should support all 4 modules at 1333 MHz and 9-9-9-24 timings. Depending on the modules, 1.5V to 1.7V is required.


Yeah, I was afraid it would be something like this. Bought the parts at the local computer shop and prevailed upon those techs to make sure I was getting the right parts and pieces. Looks like I'll learn better next time. The first cpu they sold me was a 940 which doesn't work with the am3 socket, only the 945's and up do. Ugh.

So, are there any real benchmarks to show me what the difference in speed would be between 1333 and 1600? If it's only like a 5% difference for $10, no biggie, but if it's more dramatic I'll probably want to swap these out for 1333's then. The apps I plan to run are memory-hungry more than anything so I'd take more ram over a marginal speed increase. If there's a good tool to recommend, I can just compare on my actual machine.

Thanks!
a b B Homebuilt system
June 13, 2009 8:04:56 PM

I don't always rely on the QVL, but if none of the tested 1600 MHz modules worked when using all four sockets, then that's a clear indication that it just won't work. If your local computer shop had checked, they would have known about it.

The performance loss certainly is less than 5%. http://www.tomshardware.com/reviews/phenom-ii-ddr3,2319.... Since you'll run them at 1333 MHz, you could try slightly tighter timings as long as the system is stable.
June 13, 2009 9:50:30 PM

GhislainG said:
I don't always rely on the QVL, but if none of the tested 1600 MHz modules worked when using all four sockets, then that's a clear indication that it just won't work. If your local computer shop had checked, they would have known about it.

The performance loss certainly is less than 5%. http://www.tomshardware.com/reviews/phenom-ii-ddr3,2319.... Since you'll run them at 1333 MHz, you could try slightly tighter timings as long as the system is stable.


Posting from the very system now. Thank Xod! Did not mess with the timings yet since I'd like to read up a little more on the process first. Probably not getting the absolute best peak performance right now but the system is so much faster than what I was on, I'm not missing it. :) 

Frankly, I'm amazed at how much faster the web stuff is running right now. I'd always thought most of the slowdown was on waiting for data to transfer. It looks like a good portion of the wait is just the browser trying to get out of its own way.
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