BIOS, Overclocking, VRM Ripple
We’ve reached the point where this review deviates from the standard motherboard review. How? Why? Where? I’ll cover that next!
The reason for this is that in my opinion performance numbers and benchmarks are useless to the vast majority of people. Every 990FX motherboard out there will perform within 1% or maybe 2% of this one at the same clock speeds and the same parts. The only people who should care about that 1% are the benchmarkers, and they have other requirements that are arguably more pressing as well. I’ll talk a bit about that, later.
Overclocking results have a similar issue, name that overclocking is at least 95% CPU specific unless the motherboard in question is a terrible design (insufficient heatsinks on the mosfets, usually), what I can do with this board and a FX-8150 may or may not be possible with a different FX-8150, while my chip will almost certainly overclock just as well on a different motherboard. Again this falls apart when you get into extreme benchmarking, which I will again go into later.
There are a few things that do make a big difference for overclocking and vary with motherboard models, which we will cover.
Also at this point I would like to note that Linux support for this motherboard an the Bulldozer CPU appears to be quite good, Linux Mint 11 had absolutely no issue booting up on this board, and worked perfectly!
Ok, with that out of the way it’s time to talk about…
The BIOS
For people who don’t overclock, the BIOS is likely only used once to set the time and date, and maybe not even to do that. Hence, I’m going to look at the bios from an advanced user/overclocking standpoint.
Here there are pluses and minuses, we’ll start with the pluses.
The vast majority of the CPU and ram overclocking settings are all in one section, which is excellent, and they’re clearly labeled as well, which is quite nice.
There are plenty of voltages to play with, again well labeled, and at the bottom of the list we run into the first issue: The vcore and CPU-NB voltage are both “offset” voltages, rather than specific voltages. What does this mean? It means that rather than saying “give the CPU 1.500vcore!”, you have to say “Give the CPU 150mv more vcore than stock!”.
Is it an issue? Not really, but it annoys me and feels clunky.
The other issue I ran into is that I had to set the ram timings manually to run at any speed higher than 1333 MHz. Now to be fair you should be doing this anyway, but having the AUTO settings work at high speed is always a nice plus.
Once you set the timings manually the 990FXA-UD5 can run memory quite fast. I was able to hit 2100MHz easily, no tweaking or fiddling beyond setting the timings.
This is an unheard of memory clock for AMD up till now, Gigabyte has done a good job on this board!
An oddity is that the CPU power saving features and LLC (Load Line Calibration) aren’t in the main CPU/ram section, they’re located in “Advanced BIOS Features”. Rather of an odd place, really.
Also in that section is an on/off option labeled “CPU Unlocking”, which in theory will unlock locked cores of a CPU if it has them and they function. I don’t have a CPU with locked cores so I can’t test that.
The rest of the BIOS is standard stuff, inside the PC Health section you can set alarms for any of the fans so that the computer will alert you if the fans stop, as well as being able to turn on or off the fan speed control for two of the headers, and set a CPU temperature alarm.
Overclocking
I found it very easy to overclock my FX-8150 CPU to 4.2GHz using the BIOS and the stock cooler, gigabyte made the operation quite simple. With the fan speed control enabled the computer is very quiet at idle, and still pretty quiet even at full load.
The only serious issue I ran across is the default bios settings have “Core Performance Boost” enabled by default. This automatically overclocks the CPU to 4.2GHz and raises the vcore substantially. My chip was unable to run at full load on the stock cooler at full load with the bios defaults loaded. Turning off Core Performance Boost drops the vcore down to normal, and the chip is easily overclocked to the same 4.2GHz manually without using nearly as much vcore as the bios defaults use.
LLC control is new for the rev1.1 board, it has settings ranging from “normal” (no LLC) to “extreme” (massive voltage gain under load). I found that for air overclocking the “medium” setting worked quite well.
The included EasyTune6 software works fairly well, but has an annoying tendency to reset the core multipliers if you change the bus speed. This can be worked around, but is annoying at best.
The Touch BIOS feature is interesting, but in my opinion not especially useful. Being able to change BIOS settings from windows is a nice trick, but you still have to reboot for the changes to take effect. To me it looks like a shortcut to avoid having to write a full on UEFI BIOS.
BIOS issues?
Now we’re going to take a sharp curve and talk about the board from the standpoint of benchmarking and/or more advance overclocking. Please note that the things I talk about in this section may well not apply to you, but read it anyway just in case.
The first plus for extreme overclocking on this 990FXA-UD5 is a nice open CPU area, it’s quite easy to insulate.
Early BIOS revisions were unable to disable cores, the most recent revision has added that option, thanks Gigabyte!
Unlike some previous UD5 boards, this one does not have power/reset/clear cmos buttons on it. This is disappointing.
The VRM heatsink is adequate for benching on air cooling if you give it some airflow, and the power delivery is fairly smooth, the first of the following scope pictures is the vcore taken from directly under the CPU with the computer sitting idle in the BIOS with stock settings. The second is with a full WPrime1024m load in Windows with 1.32vcore set. In both cases the horizontal lines are 10mv apart.
Just shy of 10mv of ripple at idle, and around 14mv at full load. That’s not bad at all.
The eight power phases feeding the CPU make it essentially impossible to get a clean shot of the ripple waveform, if you look closely you can see each phase firing in the second picture. The vertical lines are 20 microseconds apart and six peaks occur in that time frame, those phases are switching fast! The idle shot is 5 microseconds per line.
That about does it, now we’ll move on to the scoring section!
