You've got an older AGP-equipped system lying around. After checking out our last AGP article, you've accepted that the old girl won't be a valuable addition to LAN parties anymore. But before you go and donate it to your auntie for basic Internet use, hold on a minute. There might be some gaming goodness left in that system.
To recap, in part one of our little AGP Revival, we paired the latest and greatest AGP graphics cards with a fairly typical older platform. This system was equipped with an AGP motherboard, a dual-core Athlon X2 3800+ CPU, and 2GB of DDR memory. While the AGP bus didn't seem to be too much of a limiting factor, the CPU certainly turned out to be quite the bottleneck.
While this isn't a desirable situation to be in for a gamer, due to the limited CPU upgrade options today, it does lend itself to some affordable overclocking. The beauty of a CPU bottleneck (if you want to call it that) is that overclocking so effectively circumvents them. While graphics card overclocks usually produce relatively limited results, overclocking the CPU of a processor-bottlenecked system can show some big gains.
Let's clear something up first, though: this route won't work for everyone with an AGP system. In order for your older, overclocked processor to keep up with a higher-end graphics card, you're going to need an AGP motherboard that can handle a dual-core CPU at the very least, because a majority of new games need a minimum of two cores for good performance. That means your AGP motherboard must support AMD's Socket 939, AM2, or Intel's LGA 775 interface.
With these basic guidelines covered, let's look into the specifics of how we can squeeze the most performance from our old AGP system, while spending the least amount of cash.
For our tests, we used an ASRock 939Dual-SATA2 motherboard that supports AMD’s Socket 939 natively and Socket AM2 through a CPU upgrade daughterboard. This is a unique feature that a handful of ASRock boards offer, but the basic procedure for minimizing the CPU bottleneck in any old AGP system is the same: buy a faster CPU or overclock what you have.
We looked around locally and found a used AM2-based Athlon 64 X2 4200+ for $45. For sure, we could have worked with our existing Athlon X2 3800+, but we wanted something with a higher clock multiplier so that we wouldn’t have to push it as hard to reach our goals. Besides, the price was right and this CPU could serve our overclocking purposes nicely.
Plan on spending $100 for an AGP graphics card upgrade to kick some life into your old system, and another $50 for an overclockable CPU if your processor is an aging single-core model or an overclocking dud.
With a 2.2 GHz stock clock speed, the Athlon X2 4200+ isn't the fastest AM2 CPU our motherboard can handle, but it should overclock to 2.6 GHz or slightly beyond with a stock cooler, which roughly matches Athlon X2 5000+ specifications. We could have spent a lot more on a faster processor, like an Athlon 64 FX-62 at 2.8 GHz. But it's not really worthwhile, since we don't want to invest too much in the old system. Remember, we're overclocking to get the most out of our old hardware. It doesn’t make a lot of sense to spend enough cash to build a new one.
In our particular case, since we couldn’t find a Socket 939 candidate fast enough for our needs, we settled on an AM2-based model. Because of this, we also had to shift from DDR to DDR2 memory, since the ASRock 939Dual-SATA2 requires DDR2 on its AM2 daughterboard. This isn't typical of what most people will have to deal with, but the performance should demonstrate a best-case scenario compared to our last article. Remember, in part one, we employed a hodgepodge of memory DDR memory modules in order to hit 2GB, resulting in a lower clock. We accepted this scenario because it accurately represented the mixing and matching one might experience with an older system. After our new benchmarks are run, we'll have the opportunity to compare results. These two extremes should give us a good indication of the range of performance one can expect between a system with slower RAM versus a faster system with memory running in dual-channel mode.
Installing a CPU on a daughterboard isn't something we do every day, but the procedure was simple and it worked well enough. Kudos to ASRock for manufacturing a motherboard with literally years of longevity.
With everything running smoothly, it came time to overclock the beast. We're not looking for a extreme tweak here, but we want to achieve a nice boost that will provide meaningful benefits in our gaming tests. Additionally, our build is only valid if it won't cause overheating with the CPU running 24/7. We targeted an overclock of 2.6 GHz, which is a 400 MHz increase from the stock Athlon X2 4200+. Since the Athlon X2 5000+ runs at 2.6 GHz and has the same architecture and cache configuration as the Athlon X2 4200+, the resulting performance should closely demonstrate what an Athlon X2 5000+ would enable.
To get this speed, all we had to do was alter a few settings in the BIOS. We increased the reference clock to 237 MHz, up from the stock 200 MHz. With the Athlon X2 4200+’s multiplier of 11x, this gave us a CPU clock speed of 2,607 MHz. For stability's sake, we didn't need to add any CPU voltage, but we lowered our HyperTransport multiplier to 3x from the stock 4x, giving us a HyperTransport speed of 948 MHz after the overclock (very close to the stock 1,000 MHz). We also played with the memory speed and set it to 333 MHz in the BIOS. Since this sets the memory speed to 333 MHz at the stock FSB speed of 200 MHz, our actual memory frequency ended up as 372 MHz (744 MHz DDR). All of these settings are quite conservative, as we want to demonstrate something that an average user can achieve without difficulty.
There is one more clock speed we could tweak: frequencies on the new AGP Radeon HD 4650. Unfortunately, there’s not much to report here. The beta drivers included with the card didn't support ATI’s Overdrive feature. With the nice non-reference cooler Gigabyte included, it's a shame we weren't able to unleash the card's overclocking potential. Perhaps in the future, the AGP Radeon HD 4650 will be supported by AMD's Catalyst drivers and Overdrive.
Once again, we're using Windows XP 32-bit in order to compare apples-to-apples versus our previous Athlon X2 3800+ tests.
Note that the Athlon X2 3200+ is designated as a CPU at 2.0 GHz, and the overclocked Athlon 64 X2 4200+ as a CPU at 2.6 GHz in the charts in order to save some space.
| Test System Configuration | |
|---|---|
| CPU 1 | Athlon 64 X2 3800+ |
| CPU 2 | Athlon 64 X2 4200+ Socket 939, 2.2 GHz o/c to 2.6 GHz, 2 x 512 KB Cache 237 MHz FSB, 948 MHz HT |
| Motherboard | ASRock 9393Dual-SATA2 |
| RAM 1 | Patriot EP PC-3500 (CL2.0-3-2-5) (1 x 1 GB) Kingston KVR PC-3500 (CL3.0-3-3-8) (2 x 512 MB) Samsung PC-2700 (CL2.5-3-3-7) (1 x 512 MB) |
| RAM 2 | A-Data PC2-6400 (CL2.0-3-2-5) (2 x 2 GB) DDR2-800 at DDR2-744 CAS 5-5-5-15 |
| Graphics | Radeon HD 4650 AGP - 600 MHz GPU, 400 MHz Memory, 1 GB DDR2 |
| Hard Drive | Western Digital WD1200JB |
| Sound | Integrated Audio |
| Network | Integrated 100 Mb Networking |
| Power | Nextherm PSU460 |
Software | |
| OS | Microsoft Windows XP Professional 32-bit SP2 |
| Graphics | Radeon HD 4850 PCIe, Radeon HD 3850 AGP: Catalyst 9.6 |
| Benchmark Configuration | |
|---|---|
3D Games | |
| Left 4 Dead | Version 1014, Custom THG Benchmark |
| Crysis | Patch 1.2.1, DirectX 9, 32-bit executable, benchmark tool |
| Tom Clancy's H.A.W.X. | In-game benchmark |
| World in Conflict | Patch 1009, DirectX 10, timedemo |
| Fallout 3 | Custom THG Benchmark |
| Far Cry 2 | DirectX 9, 32-bit executable, benchmark tool |
Here's where we expect things to get interesting. Will the overclocked CPU unleash more performance or will Crysis be too bottlenecked by the graphics subsystem to show any gains?

There's a lot of data to sift through here, but the most obvious conclusion is that the Athlon X2 3800+ severely bottlenecked the AGP Radeon HD 3850. However, the CPU change doesn't seem to have much of an effect on the Radeon HD 4650 cards. Apparently, Crysis was already choking these graphics cards, even with the Athlon X2 3800+. Let's see if upping the physics detail has any effect:

If you look at the previous results, you can see that upping the physics detail has almost no effect on the simulated Athlon X2 5000+ CPU. Compare this to the Athlon X2 3800+ CPU, which definitely took a frame rate hit when physics detail was increased. This indicates that the higher-clocked CPU is shifting the bottleneck back to the graphics cards.
Also, as the resolution is raised, the bottleneck quickly moves to the graphics card. This means that the gains from the faster CPU had the greatest impact at 1280x1024. Having said that, the AGP Radeon HD 3850 was able to leverage its higher graphics performance across the whole spectrum of resolutions.

Left 4 Dead is clearly limited by the Athlon X2 3800+ CPU--look at the difference 600 MHz makes. Our Athlon 64 X2 4200+ at Athlon 64 X2 5000+ speeds is doubling the frame rate. The game still appears to be CPU-limited with the performance topping out similarly across all of the graphics cards, but at 60 frames per second (FPS), the CPU bottleneck isn't having a detrimental effect on playability.

With anti-aliasing (AA) and anisotropic filtering (AF) enabled, performance is still multiplied, except, strangely enough, for the AGP Radeon HD 4650. We can't easily blame this phenomenon on the AGP bus, because the AGP Radeon HD 3850 is still outperforming the PCI Express (PCIe) Radeon HD 4650. Perhaps the AGP Radeon HD 4650's beta driver is at fault here.



Just like Left 4 Dead, Far Cry 2 sees a massive benefit with the overclocked CPU. Suddenly, the game is running smoothly at 1680x1050 with the Radeon HD 4650 and Radeon HD 3850. The Radeon HD 3850 even manages to give us good performance at 1920x1200.



When detail is raised to Medium quality levels, the Radeon HD 4650 cards take a notable hit, but the Radeon HD 3850 manages to keep performing well up to 1920x1200. Take a close look at the Radeon HD 3850's minimum frame rates. Even at 1920x1200, it's pulling almost 30 FPS during the slowdowns.

The H.A.W.X. results look similar to Left 4 Dead. This is a CPU-limited game that can't quite get by with the Athlon X2 3800+. However, a 600 MHz frequency increase really wakes things up.

Even at the highest settings, H.A.W.X. plays well on the Radeon HD 4650 and Radeon HD 3850 all the way up to 1920x1200.



Fallout 3 is a great benchmark to demonstrate how average FPS alone doesn't tell the whole story. At 1280x1024, look at the difference in average frame rates on the Radeon HD 4650 cards. They don't change much with the CPU overclock. However the minimum frame rate gets a massive boost from the faster CPU. Minimum frame rates are more important than average frame rates here because they represent the worst-case scenario (how slowly the game runs when things get busy on the screen). Choppy performance during intense sequences most certainly sours the gaming experience, even if averages trend higher.



At high settings with 4x AA and 8x AF, the CPU overclock accomplishes a lot less. This is because the graphics cards have become the bottleneck when these image quality enhancements are turned on.

As we can see, the overclocked CPU adds about 15 W to peak power usage on average, but idle power usage remains similar to the stock-clocked Athlon X2 3800+.
So, it looks like we've answered the question we set out to explore: an aging dual-core CPU is no longer enough to run the newest games, but even an old Athlon X2 4200+ can remain a viable gaming option when it's overclocked a little. Don't donate that AGP PC just yet, because with an inexpensive CPU, a little tweaking, and an upgraded graphics card, you might have a nice gaming rig for your buddy to use when you invite him or her over for a LAN party.
Exactly what upgraded graphics card are we talking about? The fastest AGP card we've tested is ATI's Radeon HD 3850, and you can get them for under $100. Unfortunately, the AGP flavor of the Radeon HD 4670--an even newer board based on a modern GPU--was released after this review was written. We know that the PCIe version of the Radeon HD 4670 is slightly faster than the Radeon HD 3850, and slightly slower than the Radeon HD 3870, so we can make some educated guesses as to it's relative performance. Since the PCIe version of the Radeon HD 4650 performs similarly to the AGP version of the same card, we can safely assume that the new AGP Radeon HD 4670 will perform closely to the Radeon HD 3850--perhaps even a little faster in most situations, and perhaps a little slower in others.
With the new AGP Radeon HD 4670 as low as $115, and the Radeon HD 3850 as low as $95, which do we recommend? Assuming these cards perform similarly, we'd choose the cheaper one, as we think the CPU bottleneck from the older AGP systems is going to limit both of these cards. However, the availability of Radeon HD 4000-series cards on the AGP bus is a telltale indication that the AGP Radeon HD 3850 is in the process of being phased out. Also, keep in mind that the AGP-based Radeon HD 4670 will likely drop in price over time, as there is a price premium associated with new products.

So, what about the Radeon HD 4650 we tested here? As our benchmarks showed, it's a fine upgrade from an older card like the Radeon X700 and similarly-performing boards (GeForce 6600 GT and Radeon 9800 XT). Having said that, the AGP Radeon HD 4650 is new and still suffering from out-of-the-gate higher pricing. At $80 to $90, it costs almost as much as the Radeon HD 3850. When things settle down and the price gets closer to where the PCIe Radeon HD 4650 rests, the AGP Radeon HD 4650 will be a better buy. It's also likely that future Catalyst drivers may support these cards, and perhaps even enable desirable overclocking functionality.
Regardless, it is nice to see that even as AGP systems fade into the horizon, they are being supported with more modern graphics cards. Clearly, there is enough of a market to warrant bringing these products to market. However, at the same time, the powers that be seem to have decided that it isn't worth putting the fastest GPUs on AGP-based cards.
What we’ve seen indicates that, in a couple of years, games will require CPU speeds faster than what an older chip can deliver, even when overclocked. Thus, we can't help but think that we have already passed the pinnacle of AGP gaming with the Radeon HD 3850. Accelerated Graphics Port, you've been good to us, and you continue to provide reasonable mainstream performance, but I can't shake the feeling that I might not be reviewing you again...
Thanks for all the good times. I will remember you fondly.



