Hello, I'm new to the forums but I just built a brand new computer with the parts listed below. AMD Phenom 9500 CPU GIGABYTE GA-MA790X-DS4 MOTHERBOARD EVGA 512-P3-N801-AR GeForce 8800GT 512MB VIDEO CARD Crucial Ballistix (4 x 1GB) 240-Pin DDR2 SDRAM DDR2 1066 (PC2 8500) RAM SAMSUNG (2) SpinPoint T Series HD501LJ 500GB 7200 RPM HARD DRIVES Sony NEC Optiarc 20X DVD±R SATA LightScribe DVD BURNER OCZ StealthXStream OCZ600SXS ATX12V / EPS12V 600W POWER SUPPLY COOLER MASTER Centurion 534 RC-534-KKN2-GP CASE ViewSonic X Series VX2245wm 22" Widescreen MONITOR Logitech G15 v1 KEYBOARD Logitech G7 wireless laser MOUSE Windows XP Pro 64-bit edition SP2 OPERATING SYSTEM I had it up and running without any OCing or modding and got a score of ~10300 on 3DMark06 (4 tests over 3 reinstalls of windows all gave similar results). I noticed that, on POST, my RAM was registering as DDR2 800 and I decided that, since Crucial guaranteed that it would run at 1066 5-5-5-15, I would up the speed and cut down the timing. Now, I am pretty computer savvy but this is my 1st foray into OverClocking of any kind. I went into the BIOS, got into the RAM section, changed the multiplier from 4.00 to 5.33 (changing the RAM clock from 800 to 1066 MHz). Then I changed the timings from AUTO to MANUAL and knocked em down to 5-5-5-15. Restarted my comp and it basically failed miserably. I got a few bad sounding beeps, my computer restarted and it, appears, that the BIOS was kind enough to reset the RAM settings for me. So I went back in to the BIOS upped the multiplier back to 5.33 and left the timings on AUTO. This time the computer booted into Windows but it ran INCREDIBLY slowly (15+ seconds to register a mouse click or keyboard press). Also, my harddrive was making an audible click every 5 seconds or so. I reformatted my HDD and reinstalled Windows and it booted up ok. Except now I get a score of ~8200 (2 tests) on 3DMark06 and my motherboard complains of either a MAIN BIOS CHECKSUM ERROR or BACKUP BIOS CHECKSUM ERROR on upwards of 75% of the times I start the computer. On that 25% when it doesn't happen it boots into Windows fine. I have tried flashing the BIOS (it is now version F4e) and I have tried taking out the CMOS battery to reset the BIOS. I've also let memtest86+ run for about 4 hours (about 4 passes) and got no errors. My best guess is that this BIOS CHECKSUM thing is more of a coincidence (then as a result of my changing the RAM timings) and that my MOBO is shot. My plan right now is to call Gigabyte on Monday and then, most likely, RMA the thing on Tuesday after Gigabyte isn't able to help me. I would appreciate any suggestions on the follow... - how to go about diagnosing or fixing this BIOS CHECKSUM problem. - why did my RAM timing changes fail so miserably? - are there any RAM settings saved on the RAM itself or is it sort of "passive". - any opinions on whether my meager overclocking attempts could have damaged something? - any other reason I would see a ~20% performance hit on 3DMark06 besides my mobo is fecked or I ruined my RAM somehow? Thanks, Sean

1st of all, why do you keep formatting & reinstalling? 2nd, if you were to check your manual or the memory support list at the Gigabyte website, you'd find this: "Model Name: MA790X-DS4 DDR2 1066(downgrade to DDR2 800)" http://www.gigabyte.com.tw/FileList... "(Note 2) Whether 1066 MHz memory speed is supported depends on the CPU being used" "Crucial guaranteed that it would run at 1066 5-5-5-15" - that may be true, but AMD & Gigabyte are the people you need to listen to. BTW, I had a look at the BIOS chapter in your manual & didn't see anything about changing the multiplier from 4.00 to 5.33? Where is that? Is it part of the "Ctrl + F1" options? 3rd, the Phenom has got a hardware bug related to the L3 cache. AMD will soon be releasing the 9550 & 9650 which will be the "fixed" versions. There's supposed to be a workaround being developed...it will be implemented thru a BIOS update. As a matter of fact, I just had a look & the updated BIOS for your board has been available for some time. Make sure you're running version F3 or better yet, version F4E which supports Overdrive: http://techreport.com/discussions.x... http://www.gigabyte.com.tw/Support/...

All of above + check the voltage cause at ddr2 800 you only need 1.8v but to get ddr2 1066 you will need 2.2v. This would cause the system to crash! 02coled C2D Quad Q6600 @"soon OC" 1:1 Ram : CPU 4gb Elipedia @ 850mhz EVGA 680i BFG 8800 GTS 512mb - in post! 680w Thermaltake Purepower 2 x 250gb Sata2 Vista Home Premium 32bit X

It's fixed! Big thanks to jam, I wasn't aware of that L3 Cache race condition. I have version F4e of the AWARD BIOS which includes that patch. I went into the BIOS and disabled it and voila. Performance hit on 3DMark06 is gone. As for the BIOS CHECKSUM ERROR. That was fixed by properly resetting the CMOS with the CLR_CMOS jumper as per MRCOMPUTER's suggestion over at xtremepccentral.com. Thanks for the help, Sean

Bleh, while the performance hit was fixed... I am, as it turns out, still getting the BIOS CHECKSUM ERROR. Gonna get a new CMOS battery and see if that help. Sean