Extreme Llano A8-3870K LN2 Action: 6GHz Attempt

[siopao1984]

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Below is the A3870K we used after it had gone through a 5 hour LN2 session. You can see that it is still so cold it refuses to defrost even after being under our 1000W heat gun for a minute or two. The beauty of such cold is that AMD CPUs for the most parts are an LN2 Overclocker's wet dream, they lack any cold bugs and are pretty forgiving even after some harsh voltage treatment. Today we will provide sort of a recipe for how we accomplished our overclocks, so that you at home and try it yourselves!

Ingredients: AMD Fusion A8-3870K Decent A75 board with a BIOS to support the multipliers of the A8-3870K (We used ASUS F1A75-V Pro) LN2 POT or container to act like a large heatsink that you pour LN2 into Digital Thermometer that can measure to -200C, along with K-Type thermocouples Silicon based conformal coat (we used a spray on) Art eraser, you can buy this from an art store. Neoprene for the POT and the board Armaflex Insulation Thermal Paste that can withstand very cold temps (EVGA Frostbite is what we used, but there are many more) Discrete GPU A single low-density memory stick A 700W+ PSU, preferably with a strong single 12v rail Fans to blow vapour away from the board, and keep air flowing A lot of paper towel and tape for soaking up the wet Cannisters of LN2 Faith in your CPU and Motherboard, and most importantly yourself.

However we first need to go over some of the limitations of the CPU, and compare against the A3850 which we used in our Llano Round-Up. Most notably you can see that the max multiplier on the A3870K is only 47X, which means the FSB has to be increased to around 135MHz to hit 6GHz.

	A8-3870K	A8-3850
CPU Cores	4	4
Clock Speed	2900MHz	3000MHz
Integrated Graphics	HD 6550D / 600MHz	HD 6550D / 600MHz
Memory Support	Upto 1866MHz	Upto 1866MHz
Max Multiplier	47X	29X
TDP(Watts)	100W	100W
Chipset (Socket)	A75/A55 (FM1)	A75/A55 (FM1)

Read more: Extreme Llano A8-3870K LN2 Action: 6GHz Attempt by VR-Zone.com

[siopao1984]

Bench Setup:

We used the ASUS F1A75-V Pro from our recent round-up, the reason being it has an 8-Pin CPU power connector, and our other boards only had a single 4-Pin which wasn't enough. This board uses an 8 phase VRM, but just like the others it is lacking Clear CMOS, Reset, and Power buttons as well a POST code display. We cannot even measure voltage from voltage read points, but it is easy enough to find manual read-points around the board if you wanted to, however we chose not to.



First we covered the board with the silicon based conformal coat, to waterproof the board. We even did it to the back of the entire board, and then to the other side of where the DIMMs are. We also did it up to the first PCI-E 16X slot. Special care must be taken to not cover up the MOSFETs, the DIMMs, the Socket, or the PCi-E slots when coating the board. Next we apply heated art eraser to the immediate area around the CPU socket. You want to get it over and into every nook and cranny; it is used to displace air over the electrical components so that condensation cannot form. A thick piece of neoprene was placed under the CPU socket area, and then the POT’s back plate holds the neoprene to the board. We then placed a thermocouple as so that it was touching the CPU IHS. Then we added some Armaflex insulation around where the POT sits to add extra insulation.

Next, place a small amount of thermal paste evenly spread over the CPU IHS. Mount the POT and screw down the hold down, but only use as much force as your hands can provide to screw down the POT. Don't over-do the pressure (by using pliers to tighten hold down even more) or you will crack the CPU when its cold.



Once the POT is wrapped in neoprene and the hold down is secure, we have some fans blowing air up, and not down, as to remove the cold nitrogen vapours which will cause dangerous condensation after a while.

At this point you want to log into the BIOS, and then watch the CPU temperature. Let the CPU warm up to about 60C, it might take a while to get that high, and then pour in LN2 slowly to bring down the temperature. It is important you allow the CPU and POT to warm up, as it allows the thermal paste to cure a bit. You also want to watch the difference between the BIOS CPU temperature and that on your digital thermometer.



BIOS Setup:

Make sure to use a HDD/SSD you are ready to have corrupted, and set SSD/HDD mode to IDE, as AHCI seems to cause data corruption problems when going over 110MHz.



As we're clearly not saving the environment here, you want to turn off EPU and/or TPU power saving options to prevent them from interfering in the overclock.

With max APU multiplier of 47X on an "unlocked CPU" we can use a FSB of 133-135 easily so that we have some room to use 45x, 46x, and 47x to find which one fits the CPU best. So what you want to do first is set the CPU Multiplier a bit lower, we used 43X or even 37X in many cases.

At this point it would be a good idea to set CPU Voltage to offset mode, as the manual mode only allows up to 1.7v, but in windows we can increase the VID to take Vcore over 2v, which is what we need for 6GHz. We found that over 2V has very little impact on CPU OC, but 2V wasn't easy to get working straight from BIOS either. We had to use an AMD program called PSCheck to change the VID and multiplier in windows. FSB was much harder to change outside the BIOS.



We set the maximum offset we could possible select, but make sure that your CPU temperature is below -130C before doing this. We left all other voltages alone.



We maxed out the PWM settings, however we didn't use the maximum LLC setting. Current capability is very important, and so is phase control scheme.



We disable all AMD power saving technologies.



Remember to use IDE instead of AHCI, if you have already installed OS under AHCI, please re-install. You can install windows at -190C and at stock speeds, we did.



Make sure to set CPU temperature monitor to ignore, and set voltage monitoring to ignore as well as the motherboard will be uncomfortable about these extreme values and shows warnings/shutdown.

[siopao1984]

With Llano we found there to be no cold bugs or cold boot bugs, so we just kept the CPU temperature as low as possible. That type of overclocking with LN2 is pretty easy to do and fun as well, as the amount of ice that forms is pretty impressive. it is also safer for condensation as well, because everything will stay cold and frozen until you are done benching. Multiple cold and warm cycles can cause water to get into unsavory places.



Inside the POT is damn cold - LN2 boiling is a great sight!



We scrapped VRZ into the Neoprene, I am pretty sure that is going to scratch the neoprene forever, oh well. Look at how nice the screws look, it's like a winter wonder land! Make sure to use paper towels to pick up dropped pieces of snow! Notice how far away out GPU is from the cold, this was done on purpose.



Max OC with all 4-Cores, with HyperPI stability= 5.16GHz @ 1.74V



Max OC With Single Core and SuperPI Stability = 5.265GHz @ 2.01V (We know all of our cores are at 5.265GHz, but it didn't seem to matter)



Max OC Frequency with world record stability (CPU-Z validation) 5.940GHz



Max BLCK with the ASUS F1A75-V Pro with HyperPI Stability: 160BLCK @ 1.9v



So you might ask, what were you talking about at 6GHz? Next Page Please.

[siopao1984]

6GHz

Well we mentioned about 6GHz, but not in any form to make any World Records, because we weren't able to stabalize it. We kept a camera on hand at all times to take nice LN2 pictures, and when we kept trying to 6GHz, but weren't able to get it, we finally decided to snap a picture. No validation = No WR, so maybe we can try a bit harder next time!



Conclusion

We were disappointed with a couple of things - none of the Llano bioses we encountered had the capability to disable cores/modules, the maximum multiplier was only a palty 47X (which translates to 4.7GHz if the FSB isn't altered) and AMD's OverDrive software utility only offered limited overclocking options.

There is no other way to increase Vcore to 2v+ and no other way to adjust single cores on the fly without PSCheck. The kicker is that PSCheck is internal NDA AMD software that was only leaked to the public a few months ago, before that it was only something a select few AMD OCers were allowed to even use. However now it is hosted by sites such as HWBot to aid overclockers.



We would like to however commend AMD for providing CPUs without cold bugs; it makes LN2 overclocking much more fun than Sandy Bridge LN2 OCing. It also makes LN2 OCing easy enough for anyone with the proper resources to get started. If there was a cold bug or cold boot bug, novice users would have pounding headaches trying to figure things out. We liked the fact that all we had to change to hit 6 GHz and our other results was the VCore. There was no need to change other voltages.

However we also didn't tackle memory overclocking, which for Llano we hear is amazing, 3.x GHz amazing. Furthermore we didn't touch upon the integrated GPU for OC, as we didn’t feel gratified to do so. The CPU OC part was extremely fun to do, while not Bulldozer 8GHz WR fun, it was still fun none the less. We thoroughly enjoyed working with the APU, and we applaud AMD for releasing a K SKU which allows users to OC so high. The regular A8-3850 doesn’t even come close to the A8-3870K, and thus we do think AMD put some OC magic into the mix.