Random Overclocking Information

 Hi there, Vita back with a post! Probably going to be the last one for the year.

Overclocking is a weird and wonderful world. People find very creative ways to make either a processor run faster or have a better cooling solution. Both correlate quite nicely.

In old times processors just have their bare dies exposed to the cooling system. Now a lot of processors have an IHS, or integrated heat spreader, directly above the die. The IHS needs paste between the heatsink and itself and acts as a middleman of sorts.

Paste comes in many varieties but the most common form is silicone-based grease. Cheap stuff is just blobby blotchy oil. It’s really only meant to fill in the air gaps and it’s marginally better than air which is an insulator. You’d see cheap paste either in extra-budget builds or in OEM systems where they find ways to save money. Regular paste that works great is quality stuff like NT-H2. You really don’t need anything better. Nicer paste is stuff like Kryonaut which has a much finer grain and conducts heat much better. You’d also need less of it since it will spread much thinner across the surface, which is of course good. This is if you have money to spend, of course. Going even further AS5 is a common paste and is actually the only liquid metal paste a consumer who doesn’t know what they are doing should use. These also require “set” times where you need to “burn” the processor for a few hundred hours to get the paste to fully solidify and seal. With normal silicone paste this is not necessary; you actually want to keep the paste moist inside. Liquid metal also is dangerous, as if not applied successfully it can fall down into the motherboard area and start shorting circuits. What’s worse is that it will stay liquid for its entire lifespan.

Conductonaut or Coollaboratory Ultra are good examples of top-tier liquid metal pastes. Honestly they don’t really do that much but hey it feels nice to have. It’s at most a 5C drop in temperatures from good quality silicone-based paste. However when you’re squeezing every last bit of performance out, suddenly 5C is a godsend. Again as an average consumer you really should not need this at all.

What if you needed even better performance, hm?

    First you should actually focus on the cooling. Let’s assume you’re a prosumer. If even a NH-D15S isn’t enough for you perhaps a 360mm liquid cooler may be good. Past that without fully custom liquid cooling the ARCTIC LF2 420mm is the best cooling you can get without venturing outside your safety zone. If you do go further, the more surface area you can get of total radiator for a component the better, and a strong pumping system and good waterblock are required as well. However, anything listed above still is based on the room’s temperature. If your ambient Delta T temperature is 20C, then your processor can’t get any colder than that.

Before heading into subzero cooling I will revisit the processor die again. You can use a graphene pad which boasts higher numbers of watts-per-metre-kelvin. They boast somewhere around 60 W/mK. Regular paste is somewhat like 5W/mK and high-end stuff like Kryonaut is 13W/mK. The best liquid metals are in the range of a whopping 70 w/mK. However, these  conducting pads actually do worse than the high-end silicone-based pastes in practicality, most likely due to their thickness (even .1mm is still three times thicker than paste against a fully flat IHS). There’s also “diamond” pastes which are supposed to be excellent but seem to cause problems as they are abrasive and not that conductive anyways. A major cause of the issue is the size of the diamond particles.

What if you were to use a better lid? The stock IHS is pretty sucky. It’s mostly copper but nickel plated on the outside. You can delid your processor and swap out the lid for a better, perhaps full copper one. Between the IHS and die you’d use liquid metal, and then between the IHS and cooler plate liquid metal again. However here is one of the major flaws of liquid metal. Most of the liquid metal pastes are gallium-based with a touch of silver, meaning they will react voraciously with aluminum. They also damage copper although not quite as much, and nickel is pretty much the only safe surface to use them on.

But all that isn’t enough for you, eh? Well, an IHS is usually either concave or convex. AMD uses convex IHSes while Intel has a concave version. It seems convex does slightly better. You could, however, sand it flat.

Actually, I forgot to cover another issue with liquid metal so let’s hear that first. When you use liquid metal between the die and IHS, you will encounter issues as the metal may dribble about and cause shorts. You need to use silicone sealant over any of the processor’s surfaces.

Anyways back to sanding. 600 grit is the number you want to get to. You should use a sanding belt and aim to get the surface as flat as possible. You should also sand the plate of your cooler. Why not go above 800 grit? Because paste becomes useless. The holes are so small the paste can’t fill it, so either stick to 600ish or jump all the way to 3000 grit.

What if you were to… cut out the middleman? Simply remove the IHS itself and go direct-die? It’s possible, for sure. The major issue with the direct-die process is that you must go through great bounds to get a new CPU locking frame installed on the motherboard and you also have to make a new backplate for your cooler as it will sit much closer to the motherboard. This can sometimes cause issues with your motherboard VRMs as well. There are direct-die frames available for sale though so it isn’t a far-fetched idea.

No, but you want more. MORE!

    Actually, that was the furthest you could go with the normal consumer stuff available. You want more? Let’s assume we were to stay on our platform, say, the Z490 motherboard + 10900K. By technicality 10900KFs are better because they don’t have the iGPU enabled, meaning a bit of extra space for heat dissipation. Doesn’t matter that much but when you’re pushing for fractions of a Celsius it’s well worth it. Intel also had some special edition 5.7GHz 10900K ultra-bins. It’s a bit of a lie as they only hit that at 1.5ish volts, way too high for daily operation, but I’m still sad I did not win one. Whatever. If you had one of those I’m sure you could clock up a bit higher.

    I’m going to assume earlier you were using something like a ROG Maximus 12 Apex. Very nice board, focused on overclocking. We’ll have to dump that. Get something like an EVGA Z490 Dark. These bad boys are developed SPECIFICALLY for the sole purpose of overclocking. You’d have to have a few cracks in your brain to use one for your personal computer. Oh well. Anyways the Dark line has stuff like extreme voltage monitoring real-time. What you really want the board for is the amount of clearance around the CPU. By this time this system is purely for record-setting and costs an absurd amount. It’d be on an open-bench “case”. Well you can’t get any colder than ambient right? Wrong. As a consumer the next thing to go to is a TEC. Somewhere along your liquid cooling line, preferably right in front of the tubes that lead to the CPU, you have a TEC chiller. These things suck up plenty of energy. If, say, your CPU draws 300W, your TEC chiller will add another 300W to match it and another 300W to generate the coldness to boot. That’s what, 1000W? Make sure you get a good outlet. Don’t want that to pop a fuse do we?

But a TEC chiller isn’t the end of the line. Far from it (actually I take that back we’re nearly there).

There's also cascade cooling, meaning you cool the CPU die directly with a chiller of sorts, and hook it up to a watercooling system that has an external radiator (think MO-RA) that's ALSO being chilled (usually by ice, because ice is cheap and at this point you don't want to get into expensive subzero terrritory). This prevents heat shock from the cooling system and is about as far as you can get without exotic cooling.

Subzero is when your cooling system enables you to get colder than 0C. Below zero baby! LN2, liquid nitrogen, is the cooling element of choice. It costs a lot by the barrel. Actually you should be a few ten thousand dollars invested so it’s not that big of a cost is it? Bah. Loser. Come back when you have more cash!

LN2 needs a “pot”. You slap this big boy of a pot on your CPU and go set some records. All you need to do is be able to boot! Piece of cake, right? Wrong, although that’s not on topic. If you want colder than LN2 get liquid helium. It’s marginally cooler but better than not.

Remember to use some liquid metal between the CPU and pot. Your CPU should also be delidded. It’s a cold world after all, but every bit of thermal transfer is still necessary. You also need to be careful not to burn yourself. What is fun though is taking a flask of water and pouring it in to get the LN2 to vapourize and suck away some heat. Again, helium is better.

Dice (dry-ice) is a cheap substitute to LN2 if you want to set a few WRs on a budget.

I remember seeing a comical “LN2 loop” where the guy had liquid nitrogen in a normal CPU cooler loop. Extremely impractical and expensive.

Oh, did I mention liquid nitrogen condenses? You need to bring PLENTY of towels to soak up the moisture from the components, pretty much the entire back of the motherboard covered with towels and any place around the CPU too. Get a few fans blowing there while you’re at it. VRMs are gonna get hot! There's the Inferno heater backplate to help rid condensation that's pretty darn cheap; I'd highly recommend grabbing one.

Psst, a secret. Still too hot? Slather a ridiculous amount of paste around your CPU. 

 Fun fact: those pots are heavy. You should actually retain the IHS, cut a hole in it so the die can directly access the pot, and the rest of the frame remaining of the IHS will support the weight of the pot. It’s actually possible to crack the die, which is mucho not good. Anyways as I was saying somebody found a small reduction of temps happened by slathering paste all over. Do bear in mind you’re permanently ruining that motherboard and CPU for lifetime. Think of it as a mineral oil coating.

Heh, on that note, I do remember someone overclocking a 10980XE. Too bad the 10990XE was never released. Anyways they got what was it, 1000W draw on the CPU? Crazy. Even with LN2 the CPU was hovering around -10C, meaning it used so much power and created so much heat even the LN2 was barely keeping up. That’s a few hundred Celcius of heat output.

Did you know quantum computers run around 2 Kelvin? They use hyper-compressed liquid helium (type 3/4) to get that cold. What an odd world we live in, right?

I’m going to end with a different note though… did you happen to notice that there are only 2 RAM slots on overclocking boards (for mainstream platforms)? Makes it much better for RAM OCs as you get direct unbuffered traces to the CPU, one per channel. Funnily enough RAM doesn’t need much cooling, even at 1.8V where world records are set. Not even a fan is needed (you might burn your hand if you touch the heatspreaders too long but that’s it).

    Oh, that and GPU overclocking. Same story as I said but with GPUs the pots are vertical, need towels in different places, and GPUs like to have more paste and come “delidded” as stock.

I hope you enjoyed this extremely informative article.