Gigabyte 990FXA-UD5 issues

Got a rev 3.0 version of the board with the UEFI bios and am having trouble with it maintaining a constant core clock and voltage with an FX8320. (whilst under 100% load on all cores)

It seems the options C1/C6 & turbo mode need to be set to off and HPC mode needs to be on in order to maintain a constant voltage and clock speed. The problem is that once these options are set the computer doesn't post properly. At post it cuts out (like the power is pulled) and then a second or so later it comes back on and posts as normal. This occurs on a cold boot, a restart after exiting the bios, a hard reset and a normal restart from windows. (I have had it cut out a second time before kicking it properly)

Here are the specs for the machine:

Gigabyte 990fxa-ud5 rev 3.0 with bios FB. (wasn't inclined to put the beta FCb on)
AMD FX-8320
AMD Radeon HD 6850
Antec Truepower new 650
Noctua NH-L12 with both fans fitted

Temperatures in linpack when the bios is set so that it runs properly are as follows:

TMPIN0: 38
TMPIN1: 64
TMPIN2: 68

The system is set to run at 200x21 to give 4.2GHz and the voltage is set at 1.35V.

TL-DR: HPC on, C1/C6 & Turbo off (needed to stabilise voltage/frequency), pc consistently cuts out at post then comes back on and boots normally a second or two later.

Well 2 things,

1 1.35v on the core is way too low you'll find the VID on these chips is around 1.41 load CPU-z it should tell you what it is.

2 temps are a little high although there is no specified max for FX chips, is that Noctua the top down cooler as opposed to a tower? As I have one and it was as good as useless.

you should be able to run all c states and CnQ etc on such a small OC.

Try the beta BIOS (can always flash back)

The beta for the UD3 fixed its issues.

The on then off then on again sounds a bit like memory training.

Unfortunately, it is the top down noctua. There simply wasn't enough space in the antec skeleton for something more substantial. (my spare megahalems wouldn't fit) Temperatures don't end up being a problem though as it is never used for anything greatly stressful. (Basic photoshop work is about the worst it ever sees)

Never heard of memory training before. Forgot to put in the OP that it has 16GB (8GB x2) of kingston hyperX genesis 1600C9. It is running with the xmp profile loaded. The post issue is something i'd like to fix as i don't like the effect it'll have on my hard disks. I'll give the beta a go once i find a spare usb pen.

These shots illustrate the issues I'm having with APM.

APM defaults

HPC-ON C1/C6-ON Turbo-ON

HPC-ON C1/C6-OFF Turbo-ON

HPC-ON C1/C6-OFF Turbo-OFF

Basically you want APM all off and the Beta.

OK, bios FCb done. All APM features except cool 'n' quiet are now off and HPC mode on and it still cuts out during post. I've manually set everything so there is nothing left on auto, just in case.

What exactly is memory training?

Flash both BIOS so they are the same? I think I sen that solve some boards bootup and restart thing.

Memory training is when an algorithm in the BIOS that on boot up checks to see if the RAM is all working.

How do i go about flashing the backup bios? Is it via Q-flash?

Think its ALT+F12 on boot up.

Done some more research into this tonight. ALT+F12 isn't a valid command for this board (or at least the UEFI version) and there is no option to flash the backup bios in q-flash.

I tested a few other options in the bios and it seems that the cause of the start up fault is turning turbo off. (CPB-core performance boost in the gigabyte bios) Switching it back on stops the post cut out, disabling all the other power features including cool 'n' quiet seems to have stopped the frequency and voltage dancing about under load, though it isn't ideal as it no longer clocks down at idle.

Have we got a gigabyte forum rep who may be able to help iron this bug out?

EDIT:

Enabling cool 'n' quiet with turbo and leaving APM, HPC & C1/C6 off seems to sort it as the frequency clocked up to 4.2 and voltage stayed at 1.36V whilst under load. When idle it seemed to clock down to 1.4 @ 0.91V. Turbo multiplier is set to the same as standard multiplier to avoid any further issues. Would still be nice to be able to disable turbo and not have it cut out at post though, but these settings seem to do what i was looking for.

I have similar issues with my GA-990FXA-UD3 rev 1, even if I have the beta bios from earlier this year.

For no apparent reason throttles the FX8350 volts (few weeks old).
One time log in BIOS says stock voltage 1.28 the other 1.38 and next 1.48. Trying to get to stable 1.5v by putting +0.150v-+0.200v is as good as rolling dice on a casino.

So I rely on overclocking from the AMD Overdrive 4.2.6, but seems temperamental every time I upgrade the graphic card catalyst drivers since 13.10.

Never had such issues with the T1090 that worked since early 2011 at 4.2 Ghz on the first go for 2 1/2 years straight.

And that is my biggest grievance atm, because spending an extra 100 now for a motherboard to get the most out of my FX8350 requires some extra thinking.

Because I can sell the current motherboard-cpu-ram (8GB ddr3) for a bit more than the purchase of the FX8350, to someone that doesn't want more than 4.9Ghz and get a i7 3930.