Epox 8RDA+(nf2)@247fsb, need help to get to 250

[***Deimos***]

Hello folks,

Might remember me as the skeptic who doesn't believe in burn-in. After 6hr+ of "burn-in" in the form of looping Memtest86 1.51, I was still stuck at 218. A bit higher sometimes worked, but randomly gave errors. However, I made a breakthrough today, when I was searching for a jumper to make one of my 2 drives master (neither has jumper (slave), so I was searching for an extra on the mobo).

The JCLK jumper was not set, so I thought I would give it a try. Before you know it, I am up to 224. Epox 8RDA+ v1.1 with 1.76V vdd, XP2500+ using 8.5x and generic Samsung 512MB DIMM, (using 2.5-3-3-11 auto precharge), I got pretty cheap.

Max 1:1
Next, I tried CAS3 but this DIMM doesnt like that. However, 2.5-4-4-11 worked like a charm.. all the way to 236Mhz (Memtest86 1.51 test#5-3runs, SuperPi 1M, and Windows Memtest-up to 30% coverage used to test). At 238, I tried bumping up the Vcore on the CPU, the Vagp, CPU interface Optimal instead of Agressive, turning off auto precharge, widening timing to 2.5-5-5-14, trying lower multipliers, but nothing helped. I even tried putting some aluminum foil covered with seran wrap on one side, around the memory chips, and the north bridge area to provide some "grounding planes", but alas it didnt help.

Max fsb
From previous experiments I know that 75% and 60% dividers work best for high fsb. Previously got it up to 240/75 and 244/60 (before I figured out the JCLK jumper). Since memory is <<200Mhz, timings don't really matter, so I didnt change them from 2.5-4-4-11. Set 8x to eliminate CPU prob, and got up to 240/75 and 247/60. BUT, the strange thing is, SuperPI, Memtest86 1.51, Windows Memtest, they all pass flawlessly. However, 248,249,250 all cause NO POST. This is strange because problems always creep up as a few errors, escalate to many, and then finally no post over at least 3-4Mhz range.

Why would the mobo suddenly fail over 247fsb?? Any suggestions?

Currenly trying to "burn-in" at 224 1:1 2.5-3-3-11 with SuperPI 32M and Windows Memtest. Is it better to burn in at 224 with tighter timings or 247 with async mem at 149Mhz?


BTW: nf2 Vdd varies 1.744-1.76, and Vdimm varies 2.912-2.928, and without additional mods, cant raise either. CPU is not a factor since <2.0Ghz, and works up to 2.47Ghz.