Tuesday, June 1, 2021

Building a 2002-2003 Overclocking PC - Part 2



 Part 1 is here

Trying again to save the Radeon 9550

I had tried flashing the Radeon with several different BIOS ROMs that I had downloaded from techpowerup.com. Many of these would boot button  Windows would not recognize the drivers. I bought a working replacement off of eBay and harvested the BIOS from that. The dead Radeon booted with the new BIOS, but there were still artifacts.


Finally, as a last resort, I heard of some people reflowing their GPUs. Over time, a GPU may lose its reliability due to degradation between the chips and the PCBs. I read somewhere that most solders will melt at just over 200 degrees centigrade. So I shoved the card in my oven for about 10 minutes. Unfortunately it didn't help. I sadly could not repair this card and sent it off for recycling. But the replacement card from eBay will work in its place.


Pin mods and overclocking the CPU

As described in my last post I had a few ingredients to play with. For motherboards I had the BioStar M7NCD and the MSI K7N2. Both were based off the nVidia nForce2 chipset which was renowned at the time for stability, feature set and overclocking capability. For the CPUs I had an Athlon XP-M 2500+ (AXMH2500FQQ4C) and an Athlon XP-M 2800+ (AXMJ2800FHQ4C). The 2500+ is a historical overclocker. Most people from that era steered away from the 2800+ it seems, maybe due to price point. For that reason, I actually did most of my initial experimentation on the 2800+, thinking the 2500+ would fare better.

Voltage

I approached this like most CPU overclocking tasks and first found the highest stable voltage I could go, then increased the FSB or multiplier to reach the highest frequency at the given voltage.

There was one problem. The MSI allows for dual channel memory while the BioStar does not. Because of this, I decided the MSI was my favorite, and I would not do any potentially destructive experiments on the MSI board. The BioStar would be my guinea pig. However, the MSI allows you to select different voltages, but the BioStar does not. So I needed to do a pin mod to change the CPU voltage on the BioStar. The pin mod would also allow multipliers above 12.5x, which didn't end up being necessary as we'll soon see.

The pin mod guide from ocinside.de

A pin mod is a modification to your motherboard or CPU in which you short out certain contacts between CPU pins in order to change the recommended voltage, FSB or multiplier reported by the CPU to the motherboard. Some motherboards allow you to override all of these settings, and on these motherboards pin mods are useless. Other cheaper motherboards will just go with whatever the CPU reports. On these motherboards a pin mod can be necessary to override these settings. Note that pin mods are an antiquated concept and you probably can't do this in a modern computer.

I used the MSI board to find the max voltage for the 2800+ and the BioStar to explore the max frequencies. I used the pin mod to set the BioStar's voltage and multiplier to a sufficient amount (1.75 and 15x respectively) and played with the FSB to find a max frequency.

If you zoom in very close to the picture below you may be able to see the fine copper wires I placed between CPU pins.


Another consideration of the pin mod is that the voltage changes are only additive unless you cut the L11 bridge. This basically means taking a pocket knife to the right spot on your processor to un-short a few contacts on the PCB.



The 2800+ with the L11 bridges cut

Frequency

So with the bridges cut and the processor's voltage and multiplier set, I continued to experiment with the FSB to find the max frequency. This turned out to be 2.4 ghz for the 2800+ and 2.1 ghz out of the 2500+.

That was cool, but for all the hype I was expecting more out of the 2500+. This could only get up to 2.1ghz stable. So the cheaper 2800+ was actually more performant.

The 15x multiplier I was initially using ended up being useless. For awhile I thought that these processors were FSB limited (as had been my experience with modern Intel processors) but in reality they were just limited with their overall clock. So my best chip, the 2800+, is sitting pretty at 200mhz FSB and a 12x multiplier.

Overall I'm happy with the outcome. While some people in 2002-2003 were reporting excessive clock frequencies of 2.7ghz or more, I feel that with 2.4 ghz with this build, still outperforming the flagship Athlon 3200+ of this processor line, it is actually a very good overclock.

Burning Boards

Unfortunately there were some casualties along the way. After discovering the max clocks between the boards and chips that I had, I also decided to play with the coolers to see which was best. I snagged this super weird dual-fan cooler. It is loud as fuck and did not cool the CPUs any better than my $5 near-stock aluminum fins that I got from my PC recycler.


In this process I managed to burn both my BioStar motherboard and my 2500+. Long story short, if you're doing a pin mod, be really careful when replacing the CPU.

Overclocking the GPU

The Radeon 9550XL is a renowned overclocker for its time. Although my first pick died, my $25 eBay replacement worked great. So I started overclocking it.

The process for overclocking a 9550 or other similar Radeon 9xxx series card of the time is rather straightforward. These are cards that were intentionally downclocked in order to fit in a certain market segment. They have much more capability than what they are configured for. You can overclock them very easily, but the stock ATI drivers will reset the configuration. God forbid you get more performance than what you paid for. So there are certain utilities like ATITool from techpowerup that will allow you to overclock and also override the drivers. You can also reflash the BIOS to trick the computer into thinking that you have a totally different GPU with higher frequencies, but only if you find your card can support those frequencies. The 9550 or 9550XL could often be flashed to a 9600XT, but mine could not. You need to find the max supported frequencies first before flashing. 

Either way, when overclocking this card it is prudent to provide extra cooling. You want to cool both the GPU and the RAM.

Applying sticky heatsinks to the ram chips
I bought this ridiculous gpu cooler to fit into your back slot. Because the 9550 had no fans and we are about to overclock it to a fanned 9600XT model, I needed to add fans.


GPU Results

So I just cranked up the GPU as far as it would go in ATITool.

I went from the stock frequencies of 250mhz core/200mhz memory with 35 FPS average on the ATITool test to 425mhz core / 270mhz memory. That is about a 70% and a 35% overclock, respectively.



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