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Overclocking Intel's Pentium G3258 'Anniversary Edition' processor


Ludicrous speed on the cheap
— 4:44 PM on July 8, 2014

Oh man. Oh man oh man. So, yes, the desktop processor market has been kind of a sleepy place of late. The story has been Intel's consistent dominance, AMD's repeated struggles, and not much in the way of performance progress. Worse still, prices have stagnated for way, way too long. There's been precious little reason to consider an upgrade. Happily, Intel has decided to inject a little excitement into things by releasing a really cheap CPU that's completely unlocked, the Pentium G3258. I'd say they've nailed it: excitement achieved.

This new Pentium is an unlocked dual-core CPU based on the latest 22-nm Haswell silicon. The list price is only 72 bucks, but Micro Center had them on sale for $60. In other words, you can get a processor that will quite possibly run at clock speeds north of 4GHz—with all the per-clock throughput of Intel's very latest CPU core—for the price of a new Call of Shooty game. I ran out and picked one up as soon as they went on sale last week. Almost seems too good to be true. But is it? Let's have a look at how this one performs.

A 20th anniversary gift
The Pentium G3258 is an Anniversary Edition, meant to "celebrate" 20 years of the Pentium brand. Because we live in the future, it delivers way more than 20 times the performance of the original Pentium 100. The G3258's stock clock is 3.2GHz, or 32X that of the Pentium 100. And it has dual cores, so count it at 64X. Then multiply by some amount of increased per-clock instruction throughput and sprinkle in some gains from vector math and such. Don't forget the vast increases in cache and memory performance, either. You're surely at 128X the peak performance of a Pentium 100 at the end of the day, by my horrible, back-of-the-napkin estimation. Perhaps much more.

I dunno what that means, really. As a writer, though, I'm obligated to throw some big numbers at you as part of any retrospective involving the magic of Moore's Law.

Oddly enough, the Pentium G3258 is kind of a weakling at its stock speeds. Pentium is now a "value" brand, and Intel has hobbled its low-end processors in various ways in order to keep its higher-end CPUs looking attractive. Intel has disabled a bunch of features, including Hyper-Threading, VT-d, TSX, vPro, AES-NI, and TXT. The spec sheet is like an alphabet soup of "nope." Also, this chip has a relatively skimpy 3MB L3 cache, and its supported memory speeds top out at 1333 MT/s.

Thing is, in my view, that list of gimped specs is also a cavalcade of "don't care." Take the cache size, for instance. The working data set for most desktop programs is surely way less than 3MB. Larger caches are mostly helpful for sharing data between multiple cores—and with only two cores, the G3258 has less need for cache in that role. At the same time, Intel hasn't lobotomized the QuickSync video transcoding block in this little Pentium. Video encoding is one of those few common desktop tasks where four cores is a big win, but the presence of dedicated hardware eases that worry.

More importantly, where we're going, stock speeds don't matter, and an abundance of hertz can make up for a whole host of other missing features. Overclocking this thing is a simple matter of twiddling a few bits in a BIOS menu.

Punch it, Chewie.

I strapped the Pentium G3258 into my Haswell test rig, which includes an Asus Z97-A motherboard and a Thermaltake NiC C5 cooler. The cooler's specs say it can dissipate up to 230W, so I figured it should have plenty of headroom for this CPU with a 53W stock TDP.

I took the same basic approach to overclocking the G3258 that I took with Devil's Canyon, making tweaks to the CPU multiplier and voltage in the motherboard's firmware and leaving most other settings at "Auto." Asus' firmware tends to ramp up some secondary voltages automagically to improve stability while you're overclocking, and I let it do so.

This Pentium came out of the box running at 3.2GHz and 1.04V. I fired up Prime95 to use as a load test. The Asus AISuite utility reported CPU power draw under load at just 30.8W, way less than the CPU's max rating. Core temperatures were steady at 29°C. So yeah, early indications were good.

After just a few attempts, this G3258 was up and running stable at 4.8GHz and 1.375V. I tried for more, of course. The G3258 booted into Windows at 4.9GHz, but the blue screen of death came to visit once I ran Prime95. I tried cranking up the voltage to 1.4V and then 1.425V, but the extra juice didn't help. 4.8GHz looked to be the practical limit.

Which is, you know, really quite nice. Our Core i7-4790K topped out at 4.7GHz and required more voltage to get there. Heck, since the Pentium's stock clock is just 3.2GHz, this amounts to a 50% overclock. That's a magical number us old farts associate with the ur-overclocker, ye olde Celeron 300A.

At this speed, the G3258's temperatures rose to around 64°C under load, and AISuite estimated CPU power draw at 64.5W—not that I entirely trust that number. I stuck the test system on a power meter, and the whole thing draws 119W at the wall socket with Prime95 cranking. That's not bad at all. I was able to dial back the NiC C5's fan speed to about 1100 RPM, where it emits just a whisper of noise, and still keep the CPU's core temperatures in the mid-60s.

Just for good measure, I also kicked up the memory speed to 1600 MT/s, which presented no problem at all for the G3258.