Socket AM2 Motherboard Maximum Overclocked Speeds - PCSTATS
Motherboards	FSB (MHz)	Ranking
Abit FATAL1TY AN9 32x (NF 590 SLI)	353
Epox EP-MF570 SLI (NF 570 SLI)	335
Asus M2-CROSSHAIR (NF 590 SLI)	325
DFI LANPartyUT NF590 SLI-M2R/G (NF 590 SLI)	325
MSI K9N Diamond (NF 590 SLI)	325
Asus M2N32 WS Professional (NF 590 SLI)	315
ASRock ALIVENF7G-HDREADY/M/ASR (GF 7050)	312
Gigabyte GA-M59SLI-S5 (NF 590 SLI)	312
ECS KA3 MVP Extreme (CF3200)	310
MSI K9AG Neo2-Digital (AMD 690G)	306
Asus M2R32-MVP (CF3200)	305
MSI K9N SLI Platinum (NF 570 SLI)	294
Biostar TF7050-M2 (GF 7050)	285
Gigabyte GA-MA69G-S3H (AMD 690G)	284
Asus M2N32-SLI DLX (NF 590 SLI)	266
Foxconn A690GM2MA-RS2H (AMD 690G)	260
Epox EP-AF550G Pro (GF 6100)	250
Albatron KM51PV-AM2 (GF 6150)	248
ECS AMD690GM-M2 (AMD 690G)	232
Asrock AM2V890-VSTA (VIA K8T890)	230
Biostar TA690G (AMD 690G)	223
Biostar Tforce 6100 AM2 (GF 6150)	219

Welcome to the modern AMD era and Socket AM2 has introduced DDR2 into the mix. All motherboards here perform pretty well although there's not one motherboard that really sticks out in terms of overlcocking.

Socket 939 Motherboard Maximum Overclocked Speeds - PCSTATS
Motherboards	FSB (MHz)	Ranking
DFI LANParty NF4 SLI-DR (NF4 SLI)	431
DFI LANPartyUT NF4 SLI-DR Expert (NF4 SLI)	370
Asus A8N-SLI Premium (NF4 SLI)	360
Abit AN8-SLI (NF4 SLI)	343
MSI K8N Diamond Plus (NF4 SLI x16)	327
Epox 9NPA+ SLI (NF4 SLI)	324
MSI K8N Neo4 Platinum (NF4 Ultra)	312
ECS KA1-MVP Extreme (CF1600)	305
ASRock 939Dual-SATA2 (Uli M1695)	304
Albatron K8SLI (NF4 SLI)	283
Epox 9NDA3+ (NF3 Ultra)	283
Abit AN8 32x (NF4 SLI x16)	280
Gigabyte GA-K8N Ultra SLI (NF4 SLI)	277
Gigabyte GA-K8NSNXP-939 (NF3 Ultra)	270
Epox 9NPA+ Ultra (NF4 Ultra)	263
Soltek SL-K890Pro-939 (VIA K8T890)	263
ECS KN1-SLI Extreme (NF4 SLI)	260
Gigabyte GA-K8N51PVMT-9 (GF 6150)	255
Albatron K8X890 Pro II (VIA K8T890)	252
Chaintech Zenith VNF4 Ultra (NF4 Ultra)	247
ASRock 939SLI32-eSATA2 (Uli M1695)	245
Gigabyte GA-8N-SLI Quad Royal (NF4 SLI)	245
ECS KN1 Extreme (NF4 Ultra)	238
MSI K8N Neo2 Platinum (NF3 Ultra)	236
Soltek SL-K8TPro-939 (VIA K8T800)	233
Foxconn WinFast 6150K8MA-8EKRS (GF6150)	232
MSI K8N Neo4 Platinum/SLI (NF4 SLI)	232
Foxconn NF4SK8AA-8KRS (NF4 SLI)	224
ECS RS480-M (AMD RS480)	223
ASRock K8 Combo-Z/ASR (Ali M1689)	221
MSI K8T Neo2-FIR (VIA K8T800)	220
Gigabyte GA-K8NXP-9 (NF4 Ultra)	217
Foxconn NF4K8AC-8EKRS (NF4 Ultra)	216
Gigabyte GA-K8NXP-SLI (NF4 SLI)	214
Asus A8N-VM CSM (GF 6150)	213
ASRock 939NF4G-SATA2 (GF 6100)	207

The Socket 939 era introduced mainstream Athlon64 users to dual channel memory and this era is ruled by DFI. The LANParty NF4 SLI-DR and LANPartyUT NF4-SLI-DR Expert motherboards even now are two of the best overclocking motherboards in the history of overclocking.