Actually, they probably do front-run trades, just indirectly. Not robinhood themselves, but the exchange they route the orders too might by virtue of timing latencies to the consolidated tape. This is not specifically illegal but it is exploited.

Basically the way it works is that trading specialists with servers sitting right next to the major exchanges can arbitrage a trade that comes up on one exchange with a better price that exists on another exchange. This is in addition to payments for routing. Arbitrage in of itself is perfectly reasonable, that's how many trades can get execution. But it can be exploited in ways that slowly drain money from frequent traders without those traders actually understanding that it is happening.

So Robinhood basically just has to route the order to the worst exchange (which would likely be BATS) and stays just on the legal side of the law. Since robinhood's investors are idiots who day-trade, the cumulative payments and losses from poor order flow execution and delays wind up being significant.

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In anycase, as a long-time investor myself it is very obvious to me that robinhood is exploiting the stupidity of its investor base. People with no experience trying to execute complex options trades (or even normal trades using 'intelligent' trading modes such as stop-loss orders) are virtually guaranteed to lose all of their money. Experience rules the roost here. Gambling addictions make it worse. Particularly when options are used... it is very easy for an inexperienced retail investor to see a few 'wins' from their day-trading and unconsciously discard the losses... not realizing that they are actually taking on inordinate risk and losing their nest-egg until they've actually lost most of it.

-Matt

Consider that it is evangelism. Saying "We did this, we're a big investment bank" implies "It's OK, and you should do it too". I've heard people refer to arguing a vendor to lower a price as "jew them down". Enough with that.

"Tragedy of the commons".

Building a walled garden can be bad, but allowing free and unfettered access to an open field for everybody's use can too.

The actual ECC handling is done by the CPU, not the motherboard. So it doesn't matter if its a cheap motherboard or an expensive one. The motherboard support itself amounts to early-boot configuration of the memory controller by the BIOS.

For AMD, all AGESA updates (part of the BIOS image) as of around 2 years or so ago included full detection and enablement support for ECC on Zen, Zen+, and Zen 2 platforms.

There really isn't much of a distinction between 'cheap' motherboards and 'expensive' motherboards any more these days. It really just comes down to overclockability and how beefy the VRMs are and after that you are simply paying for board features.

In fact, there is almost no distinction between commercial and consumer motherboards any more these days either... it again just comes down to what bits of hardware the mobo maker puts on the motherboard. So, e.g. any modern AMD motherboard with IPMI is effectively server(colo, machine-room, rack)-capable.

-Matt

That's not really how it works. Both file data and filesystem meta-data is cached in memory. If you have 128GB of ram, then that's up to potentially 128GB worth of data and meta-data subject to bit-rot.

Many modern filesystems must update significants amount of meta-data whenever they synchronize modifications to storage. Even small modifications can result in hundreds of kilobytes being written to storage. Much of that is meta-data that had been cached in ram and then modified as part of the topology sync.

You certainly cannot depend on getting 'application errors' when ram goes bad. That sort of thing is far more likely if the CPU messes up (e.g. due to an unstable overclock for example). Bitrot in ram can be far more insideous.

-Matt

Unless you are gaming at a low resolution like 1080p, or have an extreme refresh-rate monitor (120hz or higher), the fps differences are irrelevant. And even if you do, if you game at any decent resolution (1280p maybe, but mostly 1440p or higher), the game will be gpu-bound and the differences will not really be noticable.

I look at it this way... why spend an extra few hundred dollars on an Intel chip when you could instead spend that extra dough on a better GPU or more memory and still get a CPU that's just as fast? Intel just isn't price competitive against AMD any more these days. So unless you are on an unlimited budget, AMD is the better choice.

In anycase, PBO isn't going to do much better than stock settings. It really comes down to how much power you are willing to burn to get performance, cooling, and memory, and that's it. So you really need to line-up the balls to lift-off from stock settings. i.e. you need to use DDR 3800 (3733) (i.e. max out the IF in 1:1 mode) and a good liquid or tower cooler, along with good case cooling for the VRMs, to see a performance uplift vs stock.

The same is true for a modern Intel CPU these days as well. Though it is modestly easier to O.C. an Intel chip the power consumption goes into insane-land a whole lot quicker. It often comes down to just how much power (and thus heat), and noise you are willing to tolerate to get the O.C. you want. For many people it just isn't worth the heat and noise.

-Matt

In terms of the value of ECC, there are several components to answering this question. The first thing to note is that DDR4 has error detection and retry for physical trace errors built-in so normal non-ECC DDR4 will be considerably less error-prone than non-ECC DDR3 (or earlier) ever was.

In terms of whether the ECC helps on top of that, the answer basically comes down to a combination of the use-case, amount of memory installed, and uptime.

So, for example, I would never even consider putting non-ECC sticks into a thread-ripper system with loads of memory in it. That's just asking for bit rot to happen. I will always use ECC for any system with lots of storage (it doesn't have to be a NAS). For example, my home server. The last thing I want is for a large multi-terabyte filesystem to become corrupted because machine memory got hit by a cosmic ray.

But, say, my two primary desktop systems, which I only use for chrome, xterms, games, and stuff like that, do not have ECC in them. Most of my test boxes do not either. The kitchen machine we use to lookup recipes doesn't either.

The nice thing about ECC in a modern AMD machine is that it 'just works'. You still have to use the right kind of course. Ryzen and Threadripper take unbuffered DIMMs while EPYC takes registered DIMMs.

-Matt

Yes, basically all AMD motherboards that take Zen/Zen+/Zen2 architecture cpus support and implement ECC. This includes many of the original Zen mobos which did not have it enabled in the BIOS but subsequently made the feature available after a BIOS update.

The main trade-off is that virtually no ECC sticks are certified for overclocking out of the box, meaning that you have to overclock them yourself if you want to match non-ECC DDR4 that you can buy OCd out of the box. This isn't difficult to do, but is not everyone's cup of tea. And, generally speaking, most people wouldn't notice the improvement in performance anyway.

All Ryzen and Threadripper systems take unbuffered DDR4 (ECC or non-ECC). All EPYC systems take registered DDR4 (ECC or non-ECC). Not sure if you can stick unbuffered sticks into an EPYC but you definitely cannot stick registered sticks into a ryzen or TR mobo.

-Matt

Agreed. The last 20 years have not been kind to this place.

We will know if GM built a bettter car battery in 8 years or so. I am sort of dubious, because it's more like your cell phone battery than a lithium car battery. It uses cobalt. GM brags that their EV battery uses less cobalt "than other EV batteries", but Tesla uses none. We know that Tesla batteries last. It will take a while to know that about GM batteries.

Musk is great. He took a lot of things that everyone knew about and nobody would dare to do, and made them work from a business perspective. We need lots more people like that.

Interesting reference:

Blast wind: At the explosion site, a vacuum is created by the rapid outward movement of the blast. This vacuum will almost immediately refill itself with the surrounding atmosphere. This creates a very strong pull on any nearby person or structural surface after the initial push effect of the blast has been delivered. As this void is refilled, it creates a high-intensity wind that causes fragmented objects, glass and debris to be drawn back in toward the source of the explosion.

Here. I found several on the web with a single search.

The problem is getting people to build it exactly as the computer models it :-)

I would think that welds are quite chaotic in nature. The heat changes the crystal structure of the steel, the welds are not uniform, etc.

Steel is really complicated stuff. It's a matrix of iron alloy and hard nonmetallic crystals like carbides. The iron alloy can have five different crystal structures, and can transition between them through heating - which welding does. There is also thermal stress from welding, which you can relax by annealing, but annealing the entire vehicle is not practical.

The cryogenic nitrogen used in the test is very cold, as you can see by the frost on the vehicle. Atmospheric pressure is only 14 pounds, so if you pressurize to 14 pounds greater than you intend in space, you get equivalent stress on the vehicle. The final test is to actually send it to space.

Cryogenic nitrogen. The force of it rushing out creates a vacuum.

The explosion is seen to start in the side of the vehicle. The lower arrow is where it starts.

A blowout on the remains may correspond to this.