Conclusion - Samsung Wins DDR-400 Battle
With very few DDR-400 modules on the market at this time, Samsung have defiantly put together a super high quality module that isn't officially supported by the JEDEC. Compatibility wise, the Samsung DDR-400 module worked in every board we had, and ran DDR-400 in every board that supported the speed by default or by overclocking. Stability wise I couldn't fault it, and overclocking, well 450Mhz is the highest I have ever seen from system memory to date. Being able to outperform the current king of DDR memory, Corsair, Samsung has my total seal of approval.
Geil on the other hand have basically slapped together a DDR-266 module and have tried the old, "cool it better, sell it for more" tactic. Geil DDR-400 is in my honest opinion a DDR-266 module overclocked to the limit, with a very low performance score and extremely unstable without their heatspreaders, you see that it's hard to choose this memory for hardcore overclocking.