I’m fortunate in that I’ve got 2 of these motherboards, so I’m very much certain that doing the BSEL mod on a CPU and then sticking it in this motherboard *won’t* work.

Of course I’m unfortunate in that I’m stuck with 2 of these boards. Oh well.

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The P5KPL-CM is a Socket 775 motherboard, and the biggest problem you’ll come to when overclocking is that the motherboard makes it very easy for the RAM to limit your FSB, particularly with the processors that run at a base of 200Mhz. An example is the E2140 that runs at 1.6Ghz by default (200Mhz x 8).

I’ve got 2 E2140’s, and I tried modding both of them to the 266Mhz boot strap through the pin mod. I used the conductive defroster-repair liquid both times, and tried 3 of the different volt mods to go along with them (in addition to the stock unaltered voltage). At worst, you get a blank screen. At best, you get a screen screaming for a disk with the BIOS and frantically checking your CD-ROM/USB drives for a bios rom.

After the many failed attempts, I did a little searching and found that this is typical of the P5KPL-CM. It just won’t accept a CPU that’s been BSEL modded. My results mirrored what many others have found.

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Why this is a problem…

The big issue is that at the 200Mhz boot strap, you get 2 options for the RAM aside from AUTO – 800 and 667. This is a lie. The lie is repeated on the boot screen. You’ll need to use Memtest86+ or CPU-Z to see the real values when overclocked. Choosing one of these just picks a ratio for you. 800 is 1:2 (200Mhz –> 400Mhz = DDR2 800). 677 is 3:5 (200Mhz –>  =  333.33Mhz = DDR2 667).

That’s it. Those are your only options. Often, you’ll only have DDR2 800 RAM to go along with your budget board and budget CPU. That means you’ll end up having to choose the 667 setting if overclocking. So how much of an FSB increase can you pull before you get it to 800 speeds?

240Mhz.

240Mhz / 3 x 5 = 400Mhz which is DDR2 800.

Incidentally, if you look around, most people hit a wall around 240-250Mhz. It’s the RAM. The motherboard won’t allow a better mem ratio on the 200Mhz bootstrap.

Getting the most out of your overclock:

• The ability to change the RAM timings is under the Northbridge Chipset section of the BIOS. 6-6-6-15 is the loosest you can go. Do it.
• Obviously, set the “667” speed for the RAM to get the most headroom possible.
• Crank up your voltages if need be – WARNING, my settings didn’t fry my parts, but they could fry yours! Be very careful.
  -I cranked up 3 of them to the max setting (there are only 1-2 settings for each). The E2140 I’m using didn’t get very hot (neither did the northbridge with this CPU) so I wasn’t very concerned about maxing these.
  -I turned the RAM setting to 2.0 volts. I did try 2.25V, but that’s dangerously high, and didn’t improve my results (RAM heatsinks got quite hot though – don’t even dare to try 2.25V if you have basic RAM with no heatsink).
• If you happen to have DDR2 1066 RAM around, that’s your best option. The RAM should be able to handle an FSB of 320 (320Mhz / 3 x 5 = 533.33Mhz which is DDR 1066). That said, don’t get your hopes up. Using the 200Mhz boot strap, that’s a fair bit of an overclock on the P5KPL-CM.
• If you have multiple sticks of DDR2 800 RAM (perhaps in another machine…?), grab all your RAM and see which manufacturer clocks the highest. Then mix them in the board as follows…
  My example:
  I had 2x2GB Mushkin DDR800 sticks that worked at 266Mhz FSB (ran at 444Mhz, or DDR2 888 speeds using the 667 BIOS setting)
  I had 2x2GB OCZ Gold DDR800 sticks that failed at 250Mhz FSB.
  What I did was I mixed the RAM. I put the (bad) OCZ Gold in the memory slot *closest* to the CPU, and the (good) Mushkin in the slot farther away.
  I did this on both motherboards, and they both passed Memtest86+ at 266Mhz FSB after this!
• Beg somebody to mod the BIOS. An additional RAM multiplier is available at higher bootstraps. Someone really capable should be able to bring the additional multiplier into the 200 bootstrap (or change what the “667” ratio actually points to). Alternately, they might be able to fix/disable whatever check is causing the board to crap out when it detects a CPU at a bootstrap that it shouldn’t be at (or they might be able to mod the CPU table so that it thinks all 200-fsb chips are really 266-fsb chips, though this would probably *require* you to BSEL-mod your chip to match.

Those are the only real options. If you’re itching to spend some money, a current CPU will give you the most bang for your buck (you’ll get a higher speed, although you’ll still have limited overclocking). The next best option is a new motherboard that’s more overclocking-friendly (and has more RAM ratio possibilities), particularly if you’ve got a CPU known for really high clocks at stock voltages. The final option is getting faster RAM (DDR2 1066). It’s not great bang for the buck because while the RAM will go higher, the board might choke anyway before you get to the new memory FSB limit.

Conclusion

I’m pretty disappointed with ASUS. This motherboard really should been labelled under their ASRock line. Even ECS boards (which I’ve had many of in the past and which all sucked) can apparently handle the BSEL mods. I stopped buying ECS a long time ago, and based on the last few ASUS boards, I’ve been buying more MSI and Gigabyte lately. ASUS just has too many boards with poor overclocking options, and they’ve gone from making a lot of great enthusiast motherboards to a lot of mediocre motherboards. It’s a shame when a processor known for insanely easy overclocking is barely able to get a bump on an ASUS board.

In any case, BSEL won’t work, and while you can toy with the few settings you’re given, if you want to hit the high Gigahertz, you’ll either need great RAM or an already-fast CPU. Then again, you might just want to buy a quality motherboard from another manufacturer.

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UPDATE: I was able to get to get a little farther – 285 Mhz FSB on both motherboards by disabling the onboard video and using dedicated video cards. Both were stable although I blew a power supply. 290 Mhz failed Memtest86+ although I’ve got both Mushkin sticks in the 1 machine now and am looking to see if the board will go higher.

Note that the RAM gets extremely hot at 285Mhz (DDR2 950 speeds). I have a dedicated dual-fan RAM cooler on it (the built in heatsinks aren’t enough), as I wouldn’t want to keep pushing the clocks at the temps they’ve been sitting at.

Incidentally, the OCZ sticks got the hottest by a long shot (even though they were closest to the CPU fan and would have received residual airflow). I’m surprised they didn’t melt. The power supply that fried was an OCZ also. I’m quickly losing faith in OCZ.