790i No Post + Stability issues - Calling all hardware gurus

XFX 790i Ultra
QX9650 @ stock - auto settings
4x1GB OCZ Platinum 10666 @ 1.8V - auto settings
ThermalTake 1200W Toughpower

Problem #1: No Post on cold boot.

Every morning the system will either not post at all, or not complete post, and will require either several reboots and/or a complete system discharge (unplug, hold in power button) in order to get it to POST and boot into windows.

After a successful POST, rebooting will always work just fine with any BIOS settings, but if I turn it off for even 10-15 minutes it will not POST again.

I have tried every combination of components, bios settings/timings/voltages, 2 sticks of RAM in either slot, etc etc, the No Post still happens every morning. This is just with Motherboard, CPU, Power, RAM, and I have tried with 2 different video cards with the same result.

This weekend I will be trying the computer in a different physical location on a different power outlet in a different room.

So for this one, do you guys think it is the power supply? I am starting to think that, the fact that it will POST successfully if I discharge all the power has me wondering. There are other people on other message boards reporting similar problems with this motherboard.

Issue #2: In-Game Stability

With 2 GB of RAM (2 Sticks) the computer has great stability, with 4GB there is a certain amount of tweaking required to get stability (still haven't found the sweet spot).

When the computer POSTs, even with 4GB, with the right settings I can get Prime95, Everest, Super Pi, OCCT, or any other number of programs to run perfect for 12+ hours. Memtest passes all the RAM without any problems.

Occasionally I will get in-game lockups though with the event viewer only stating that the previous shutdown was unexpected...no blue screens, no error messages, just hard-locks. They happen with any one of the two video cards running by themselves with 4GB or RAM, but I haven't been able to get lockups to occur on 2GB, or even with 4GB and relaxed timings.

Now, this is looking like what everyone on other forums has been saying, that the 790i NorthBridge has issues with 4 DIMMs which might be overcome by modifying voltages in the bios.

Plus there is the first issue which might be power related.

I just don't know if its power, or motherboard, or what the problem is and I am looking for opinions to try to figure out why its happening.

I am going to run on 2GB until I get the NO POST situation figured out and then deal with the 4GB issue after that.

I am also going to get my hands on another power supply to swap out with tommorow if changing physical locations doesn't do the trick.

Its been 2 weeks testing back and forth, so im pretty desperate at this point to get it working so I can just start working with it normally. I have been building computers for myself and many others for several years, and this is definitly the most trouble I have had. If it matters, I am also CompTIA A+ IT Technician Certified (2007/8).

It makes logical sense to me that if the computer will run for 12+ hours at 100% CPU and heavy memory loads that all hardware components are good to go...so I am thinking that the problem with the no POST is only a power issue, and that once fixed, I could easily nail down the stability issues with simple BIOS tweaks.

Thank you in advance for any help.
6 answers Last reply
More about 790i post stability issues calling hardware gurus
  1. #1. Could be the psu, but Toughpower is one of the best. Does the bios support the cpu? Have you increased the vdimm? voltage for ram should be higher than stock for 4 sticks. 1.9-2.1v would be ok. If you can't get the pc to post at all, try each stick of ram in each of the slots. Also, try switch the psu to off & press the case's power button for a few secs.

    #2. It may sound like a memory issue, but your ram checked out in numerous tests for hours. You can rule it out. I think it may be the bios settings. The newer chipsets offer more than just new features, but also more control over voltages. It's no longer just the vcore, vdimm, vmcp(SB) & vssp(NB). There are more voltage options. Screwing up one of them will render your pc unstable.

    Take my pc for example. If I screw up one voltage like CPU VTT (too high is the usual culprit), my pc can boot up xp & stuff, but will randomly freeze or restart. Took me a while to stabilize the o/c. I used too high a CPU VTT value & too low a NB/SB voltage.

    Oh yeah, if you're running Vista, get the update for 4GB+ ram. Otherwise, Vista won't be stable.

    Search for answers at evga forum. I know it's a different brand, but they use the same reference board. In fact, some of them use XFX bioses.


    To sum it up, up vdimm, update windows & check out evga forum.
  2. hong kong says it all
  3. Installing 175.7 helped eliminate most of the same problems your having the only thing it does now is the graphics driver stop every hour exactly but the machine resets fine for anther hour.
  4. So I have swapped every component, rebuilt the system, tried older bios revisions, disconnected all headers and just used the power button on the motherboard...still the problem persists.

    I think its going to be my second replacement board (third board overall)...

    There seem to be lots of people RMAing 2-3 boards before getting one that actually works :(
  5. I thought my problem was solved but the next day the same problems, I still believe this is a graphics driver problem but I'm still thinking of sending my board back just in case.
  6. There are people everywhere having problems with the 790i Reference boards, and it seems to be crummy North Bridge and Memory Controller circuitry...as well as powergood circuitry...

    Honestly I think I am going to have to just suck up the ~$350 that I spent on it, and spend another ~$450 on the Asus Striker II Extreme...at least that has solid state capacitors, isn't based on the reference boards, and not nearly the amount of negative posts as the XFX or EVGA reference boards.

    What a nightmare.
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