看到您這段話, 只好懷疑自己的記憶
連忙去 Intel 網站找了一下 datasheet, 找到 82815 GMCH 的 PDF
Page 67 寫著:

"................... The programming of these bits should be based on DRAM density (x8 or x16), DRAM technology (16 Mb, 64 Mb, 128 Mb or 256 Mb), rows populated, etc. Note that x4 and x32 DRAMs are not supported. Registered DIMMs and DIMMS with ECC are also not supported and BIOS upon detection of ECC via SPD, should report to the user that ECC DIMM timings are not supported by the GMCH. "

我指的是 VIA 694, 之前的693我也不清楚 ^^|||

所以怕有問題是
因為那時 PQI (如果沒記錯) 出了一批256MB , 約是當時其他廠牌256MB的 2/3價錢
只是有限制, 只能在 VIA chipset上用 (當時光華有商家還在報價單上特別註明)
原因就是, 它用的不是主流的 x8 memory, 可能當時它剛好有機會掃到一批便宜的 x4 memory
而如果是 x4的話, 一般高度的PCB就一定要用雙面才能做出一個 bank (當然, 堆疊式的除外)