Quick Nvidia Strap Guide

Originally Posted by EvoBeardy

Hope this is a bit clearer, it's what I've gathered with OCing.
If you go under a 1:2 ratio between your core and shaders, it won't change your settings at all.

(Requested Frequency/Actual Frequency)

Shader Straps:-

Due to ratio, can't personally go lower than>1431=1404 (with default core of 702)
1432-1485=1458
1486-1539=1512
1540-1593=1566
1594-1647=1620
1648-1701=1674
1702-1755=1728
1756-1809=1782
1810-1863=1836
1864-1917=1890
1918-1971=1944
1972-2025=1998
2026-2079=2052
2080-2133=2106
2134-2187=2160
+2188=2214 (drivers crashed at 2250)

Core 738
Can't go lower than>1476 due to ratio>nearest strap is 1458 so core strap becomes 729 to compensate (729x2=1458)

Shader Strap>Core Strap:-

1404>702-max
1458>699-705=702, 706-709=710, 710-714=713, +715>729-max
1512>710-716=713, 717-723=720, 724-725=725, 726-732=729, 733-737=734, 738-740=738, +741>756-max
1566>733-737=734, 738-741=738, 742-748=741, 749-763=756, 764-767=771, +768>783-max
1620>749-763=756, 764-770=771, 771-774=774, 775-779=778, 780-786=783, 787-788=787, 789-793=792, +794>810-max
1674>787-788=787, 789-795=792, 796-802=799, 803-806=802, 807-813=810, 814-817=818, 818-820=821, +821>837-max
1728>814-817=818, 818-824=821, 825-831=828, 832-833=833, 834-840=837, 841-846=842, +847>864-max
1782>841-846=842, 847-849=846, 850-856=849, +857=864 (Drivers Crashed at 865)

My max Core seems to be 864-ish, but basically the higher your Shaders, the higher your Core can go (up to a point of course). Obviously my Shaders can go much higher than listed, but I wanted to go as low as I could with stock Core and show the results of Shader limitation from there upwards.
If you get the second to last numbers from the tested straps, you'll have a full list of Core Straps from 702mhz-864mhz.

Memory Strap:-

995-1003=999, 1004-1012=1008, 1013-1019=1015, 1020-1021=1018, 1022-1030=1026, 1031-1032=1034, 1033-1039=1037, 1040-1048=1044, 1049-1057=1053, 1058-1063=1058, 1064-1066=1062, 1067-1072=1065, 1073-1087=1080, 1088-1093=1095, 1094-1096=1098, 1097-1101=1102, 1102-1110=1107, 1111-1121=1116, 1122-1128=1123, 1129-1139=1134, 1140-1146=1145, 1147-1157=1152, 1158-1166=1161, 1167-1171=1166, 1172-1175=1170, 1176-1180=1173, 1181-1195=1188, 1196-1200=1203, 1202-1204=1206, 1205-1209=1210, 1210-1218=1215, 1219-1229=1224, 1230-1236=1231, 1237-1247=1242, 1248-1254=1253, 1255-1265=1260, 1266-1274=1269, 1275-1280=1274, 1281-1283=1278, 1284-1288=1281, 1289-1303=1296, 1304-1308=1311, 1309-1311=1314, 1312-1316=1318, +1317=1323.

This was done with a .MKV video (Anime' ) on pause in the background to force 3D clocks (too lazy to force 'em) and a GTS 250 with Samsung Memory modules, and may or may not be the same for other cards.

Hope this helps

Thanks to Mikecdm for the initial Shader Straps which were double-checked and upped as much as my card would go for this.